Runs as expected, not tested for a long duration but seems to be perfect
I constantly get "Steam is Currently Offline" and am unable to play online. I have no idea what is causing it and why it sometimes works.

unset SDL_VIDEODRIVER; PROTON_HIDE_NVIDIA_GPU=0 PROTON_ENABLE_NVAPI=1 DXVK_ENABLE_NVAPI=1 DXVK_ASYNC=1 DXVK_HUD=compiler gamemoderun %command% -dx11 -USEALLAVAILABLECORES
Significantly improved performance after upgrading NVIDIA driver from 560 to 570.86. Had severe FPS drops and game progressively slowing to a crawl (< 15 fps) before updating the driver, butter smooth FPS after
Upgrade your driver

gamemoderun %command% -dx11
The majority of the time I play, it will freeze my discord client, my web browser, and my steam client. They have to be forcefully restarted to restore visible functionality. Unsure if this is some sort of wayland/nvidia issue or a kwin issue but it is a generally unpleasant issue that I only experience on Squad.
Rarely the game will crash. Sometimes it will crash Kwin too which crashes all of my open applications. Not frequent enough to be unplayable by any means.
I only experienced a minor difference between dx11 and dx12 mode. My impression is that dx11 is more stable though so I am sticking with it.
Despite my issues with freezing applications, I still have a pretty good time playing it. By all means try it out, just be wary you might run into a couple problems if you're on kde plasma/nvidia/wayland. Haven't tested it properly in other configurations. By all means it is playable though and the issues arent a big deal.

Worked fine just as in Windows
The game booted up fine(Though a lot quicker than Windows) and ran great. No stuttering or any bugs I noticed that weren't already part of the native game.

The game performs horribly
The game is no longer playable after the update. 10 FPS max when in a match.

unset SDL_VIDEODRIVER; mangohud gamemoderun %command% -dx11
My VRAM maxes out on certain maps and my framerates tank to oblivion.
If the VRAM issue is fixed the game is completely playable, even the modded servers.

only 1 issue, the ping of servers is all 9999, you have to change your server list filter to get the servers to show.
Game runs phenomenally. I have everything at epic settings and, despite the server ping bug, it has not so much as stuttered.

unset SDL_VIDEODRIVER; gamemoderun mangohud %command% -dx11
DX11 is mandatory. Insane FPS drops and stuttering with DX12.

With FSR 720 at 1080 and average graphics settings, the game works generally stably, producing about 60 fps in vanilla. But on the mod serve
gamemoderun WINE_FULLSCREEN_FSR=1 WINE_FULLSCREEN_FSR_STRENGTH=0 %command%
When playing without FSR and using a regular Proton, fps jumps a lot and is generally unplayable on mod servers.

%command% -dx11
Downright unplayable on many maps, huge fps drops from 10 to 0.
Unfortunately, unplayable in the current state with my setup. Definetly will try again later.

Works just like on Windows, OOTB
Just switch from DirectX12 to DirectX11 and your good //On DirectX12 theres some scenes (I only noticed with ground and buildings) where it flickers the brightness every 10-15 seconds//

Kisak Mesa/Navi driver update prevents start.
gamemoderun %command% -dx11
Kisak's Mesa/Navi drivers version: 24.3.2-kisak1-j is borked. 24.3.1-kisak1-j worked fine before the update. No change in launch config fixes the issue.

PROTON_HIDE_NVIDIA_GPU=0 PROTON_ENABLE_NVAPI=1 gamemoderun %command% -dx11
some crackling in loading screen
frames below 10 fps in menu and in game. unplayable after latest update. (from memory the game ran fine before this update)
hopefully they fix it soon, this is just not playable.

unset SDL_VIDEODRIVER; gamemoderun mangohud %command% -dx11
There were some problems when running game in Hyprland, easy anticheat was giving an error. Everything was solved with the start parameter "unset SDL_VIDEODRIVER;"

gamemoderun %command% -dx11
Audio devices do not populate in settings. Game seems to use whatever in/out devices I have selected in the Plasma desktop audio settings.

Severe stutter

gamemoderun mangohud %command%
On the Nvidia graphics card: significant freezes, serious FPS drops, extremely unstable frametime chart, regardless of the DirectX version
In general, the game works fine on Linux. However, there are problems with Nvidia graphics cards (i think it's driver issue) - very serious performance problems. I also tested the game on my PC by temporarily replacing the graphics card with the RX 5700 XT by installing the AMDGPU driver. In such a combination, the game works perfectly. It even seems to me that it works more stable than natively. Not a single freeze/lag/FPS drop. However, the problems on Nvidia need to be solved. I tested the game on both graphic cards (RTX 3070 Ti and RX 5700 XT) on same graphic settings - maximum settings, Full HD.

If you dont Change the game to DirectX11 rendering, it will hard freeze after about 30 Minutes

Runs perfectly out of the box
Install and play! No tinkering needed
EAC doesn't work without patching glib

Works fine
Had one unreal Engine crash randomly but so far it only happened once at the beginning
It is working fine, but you need to change the serverbrowser filter settings. set the max ping on the max possibility.

i'ts works
Works out of the box. Sometimes Squad patches break linux compatibility but its mostly fine.

No Issues if you know what server have good ping, as the server browsers shows all pings as 9999ms.
Server Browser Pings are all 9999ms, this makes selecting a server with playable latency trail and error.

Works perfectly fine! No tinkering. Only issue is borderless window w/ native res on GNOME sometimes cuts out a bit of the bottom
borderless windowed on GNOME sometimes cuts out the bottom part a bit

Runs well, but with some issues on launch(Microsoft VC Redistributable install script hangs).
gamemoderun %command% -dx11
This was a while ago, but I had to patch EAC as follows: wget https://github.com/Frogging-Family/glibc-eac/releases/download/release_1/lib32-
glibc-2.39-1-x86_64.pkg.tar.zst
pacman -U glibc-2.39-1-x86_64.pkg.tar.zst lib32-glibc-2.39-1-x86_64.pkg.tar.zst
Missing Textures
Missing gun textures. This also results in broken PIP scopes. This happens very infrequently.
Overall, the game runs well. 'Microsoft VC Redistributable' install script seems to hang every time steam is started and I try to run the game. To fix this I clear Steam's cache(this can get annoying).

gamemoderun %command% -windowed -dx11
Two of like 50 matches have had missing textures. Not a common occurrence.
Fullscreen with full composition pipeline (NVIDIA-only) breaks performance totally. 0.1 FPS tops, if it updates at all.
Scoped weapons stop working after the first round or so. They grind to a good 5-10 FPS. 1x weapons are fine at 120+.

PROTON_HIDE_NVIDIA_GPU=0 PROTON_ENABLE_NVAPI=1 gamemoderun %command% -dx11
With the launch options, performance is much improved than without. Much closer to windows now.
This is my 2nd post on here for Squad and it's good news. Thanks to the advice others in this thread, I've identified launch options that improve performance for me.
In the game options, set DLSS to on, set DLSS mode to Quality, Balanced or Performance. Also in the options, set "Prioritize Scope AA" as "Prioritize Scope Clarity" will disable DLSS.
With this configuration, the game runs SIGNIFICANTLY better than before and is actually playable. Credit to Paradox and John Persona 4 below.

This game works on Linux, but you may need to tweak a few things. As mentioned in other posts try changing DirectX vers first.
Switched to DirectX11
Poor FPS on DirectX12.
Stuttering on DirectX12.
There's a ping issue on the server browser displaying all servers as 9,999 ping, so you may need to change your filtering to show that high of ping if nothings coming up. I think the default view filters anything above 150. On joining the ping is fine. Since all servers have 9,999 ping you'll see the Russian/Chinese servers, so just add a language filter to get around that if you're in North America. I favorite the good one's to avoid having to search each time. Also you may need to change your DirectX version if you're having fps issues. DirectX11 works flawlessly for me. DirectX12 gave me max 30 fps. Comming from Squad on Windows this works great after only changing to DirectX11 on Ubuntu.
Runs out of the box and can play online no issues.

PROTON_HIDE_NVIDIA_GPU=0 PROTON_ENABLE_NVAPI=1 PROTON_USE_WINESYNC=1 %command% -dx12
Installed Proton EasyAntiCheat Runtime and I'm running the game using DX12 and a mix of ultra/high/medium graphics settings and Low audio quality settings (Even on Windows, lowering Squad's audio quality to Low can fix some performance issues, specially on Galactic Contention mod) and "PROTON_HIDE_NVIDIA_GPU=0 PROTON_ENABLE_NVAPI=1" to be able to use DLSS.
Works outstandingly well on my end, 0 bugs or glitches and seemingly the same performance I was getting on Windows with the same machine. I even added a controller through Steam Input to use when I drive vehicles.
It plays from around 50 fps (worst case) to 100 fps (my monitor refresh rate is 100Hz and I'm using Vsync) at 3440x1440 with Balanced DLSS.
Runs perfectly fine.
The only issue I have is the server browser. It showed no servers, removing the ping filter showed all servers with 9999 ping. Joining works as normal, only the server list ping failed.
If you have any stuttering check, check if you are using the correct Nvidia driver (no experience with AMD) or your display configuration. My stuttering issue was related to the X configuration of the second monitor. Opening nvidia-settings and setting the resolution and refresh rate of the second monitor from "auto" to its explicit value fixed it for me.

After switching maps the game would run at an unplayable speed (10-15 fps)
After switching "Renderer" to DirectX11 in the graphics settings in-game the game runs as it would on windows.

After a little tinkering, it works at least as well as in Windows. I think it's even more stable than Windows
unset SDL_VIDEODRIVER; PROTON_USE_WINESYNC=1 PROTON_ENABLE_WAYLAND=1 -dx11
Strong FPS Drops. Strong Lags.
I have installed glibc-eca. It is important to know that the AUR of glibc-eca is not up to date at this time. I would therefore recommend using the repository at https://github.com/Frogging-Family/glibc-eac/releases.
The biggest influence on the performance was to start the game with DX11. DX12 caused me extreme performance loss.
I have added some launch options but I can't say if they really contribute to the performance
Now it works really smooth! I dont have any lags anymore.

gamemoderun %command%
Proton does not like grass on the eastern european maps
the entire map gets loaded into your VRAM and after the match ends not everything gets cleaned up (memory leak)
until the devs look into the proton build, there's no way of playing for more than 2 hours straight without performance issues