perfect
PROTON_USE_WINED3D=1 %command%
PROTON_USE_WINED3D=1 %command%

had to switch to 7.0-6 for it to work, newer versions won't have it run at all.

doesnt start with new proton hotfix afiak; switch to experimental

The game doesn't seem to work with obs-gamecapture. Other than that, works well.
Multiplayer just works.
Works really well.

Runs perfectly out of the box
Game runs with proton without additional configuration
Fullscreen would shrink down to a rectangle in the corner of the screen. Only occured when swapping to a different monitor/workspace, and only on Hyprland. Repeated swapping caused a crash, also only on Hyprland. Unsure if this is a Hyprland issue or just Wayland being Wayland
runs like goode. dont even need to use GE, i just default to it
Works perfectly.
Enjoy the game. It's cheap when on sales.
It runs perfectly... even online multiplayer.. no issues at all
Runs like native
Apparently, Proton 5.13-6 was patched so that inputs work with SOCD inputs from hitboxes. However, any following Proton iteration reverted the patch and now has faulty inputs when you try to use SOCD. It is said that it will be included again in patch 7.10.
Online is great due to rollback. You can make the input lag run 1 frame faster than windows if you run the "native" version of steam on your Linux computer. Also make sure any sort of compostor is turned off for minimal input lag. This adds a lot more to both the offline and online experience.
Make sure you run proton 5.13-6 if you are using a hitbox controller or any device with Simultaneous Opposing Cardinal Directions input cleaning (SOCD), or wait until proton 7.10 comes out. To ensure minimal input lag, make sure your compositor is turned off when running the game in your desktop enviroment settings and also make sure you run the native version of steam. If done correctly, the input lag will be reduced to run even faster than the windows version!
I did not use steam's controller input feature. I do not know if that has any additional input lag if you were to use it.

No significant bugs encountered.
Works absolutely flawlessly, minus the opening movie not working due to wmp9 not working in this prefix. Proton-GE helps.
Literally just works
Maybe Glorious Eggroll would make it perform slightly better but I couldn't get it to launch on GE-10 and the default prefix runs it seemingly perfectly
Beware of Bridgets
The Proton-GE fork has fixes for this game. The game runs smooth and I cannot feel any difference as compared to playing it on Windows.
Proton-7.1-GE-2 GloriousEggroll
Proton-7.1-GE-2
Works flawlessly, no noticeable issues
Works fine :)
Just be mindful of the potential controller issue. You may need to have two gamepads ready to connect to it.
Without a controller added, it'd constantly input W and A (left and up). With one added, it inputted the same on controller port 2. I had to connect two controllers to make the issue go away. The problem was significant enough to hinder any form of gameplay until I could fix it.

Works (almost) perfectly out-of-the-box, no launch options needed
The only two issues are the opening cutscene not playing and the long connection times for rankings (both after a single-player mode as well as online on ranked mode). The former should be fixed on a future Proton update, and the latter isn't really as bad as people say (though it does also affect your ranked opponents running Windows, so be mindful of that).
Only issue is that ranked matches have long post-match screens between games that are much faster on Windows.
The previous hitbox controller issue I ran into in my previous rating is gone in Proton 6.3-5.
After a ranked match, it takes forever to send ranked data to the server before you can queue again.
This wasn't apparent until dozens of hours played online, but there are certain situations where the game won't send a down input, which is obviously very troublesome if you're competitively minded. There are offensive situations I haven't found a pattern for, but mostly this comes up in blockstun when you're blocking high and need to switch to blocking low. You can't just hit down while holding back. You need to let go of back and hit down-back, which is way riskier than how the game is intended to play. Your mileage may vary, but this happened to me, and I had to spend hours trying to confirm that it wasn't just in my head.
My fightstick if set to PS4 mode will be detected as both player 1 and 2, this causes menus to be a pain. When in PS3 mode it works as expected
Some days/patches have more crashes than others.
it works awersome now and online too sence before the GGPO it did nto wokr online now it does.
just add this as launch option to be safe: PROTON_USE_WINED3D11=1 %command%

6.1-GE-2 GloriousEggroll
https://github.com/GloriousEggroll/proton-ge-custom/releases/tag/6.1-GE-2
- Fixes Opening Movie + Background Music
Played several local and online matches (anywhere from 150-200 ping) with no issues, aside from there being a noticeable delay sending rankings after a match.
I think this is the game's fault, not Proton, but it has difficulty with full screen above 1080p. I'm on a 1440p monitor.
Literally the only issue I've noticed between Windows and Linux is that on Linux, after an online match "Sending Ranked Data" or whatever takes about 30 seconds longer. This is an odd slowdown of the online experience, but it does eventually work, so...you just spend a bit more time waiting is all.
Use Wayland.
Running with X the BGM doesn't work.
Playing using X instead Wayland get some troubles like the game don't initializing and crashing when changing game mode.
The game always crash with X, but works out of the box with Wayland.
Works fine with proton 5.13 with the GGPO public test. For my laptop had to use: PROTON_USE_WINED3D11=1 %command%
Runs basically perfect
On first few sessions the audio was noticeably crackling but the problem completely disappeared after playing some more.
I'm not sure if this is just because of the beta but the opening cutscene does not play, but no other problems at all other than that.
Luckily I have a second monitor, you can escape focus but not ALT-TAB properly, it stays on top no matter what.
Game works perfectly, online is recommended. Couch mode is hard to get 2 fightsticks working.
JUST THE START UP MOVIE, only marking this for full disclosure. Game works perfectly.
Use proton 5.0-10
I've played for a continuous hour with the Rollback beta branch. Any either compatibility layer desynced me in online. Proton 5.0-10 works well. I didn't use any other launch options.

Run into problems on proton 5.13-1, works on proton 5.0-10.
I experienced problems when running on proton 5.13-1 (Graphical Glitches, Freezing on launch, ...), no problems on proton 5.0-10. I did not test multiplayer.