Blue Mammoth Games announced that later in October that the platform-fighter Brawlhalla will be getting Easy Anti-Cheat. Thankfully, they've put up a Beta for Linux users playing it on Steam Play Proton and it works.
Easy Anti-Cheat is not yet in the main version which works as normal but once they do put it live for everyone, it would have blocked Linux players using the Windows version with Steam Play Proton. When asked on Reddit, a developer mentioned this:
Thank you for the information on this. Our intent is to support as many people as possible and this should be configured correctly to support Linux. If you are able to, please use the tech-test Steam beta and check to see if EAC loads correctly. Thanks!
Testing the tech-test Beta it myself today with Proton Experimental, it does in fact work just fine and Easy Anti-Cheat is correctly loaded. When looking in the file located here (exact location depends on your Steam Library setup) "steamapps/compatdata/291550/pfx/drive_c/users/steamuser/AppData/Roaming/EasyAntiCheat/service.log" it notes this nice and clear:
[EAC Setup]  [11:20:32:514] [Info] Process started, running as admin: true.
[EAC Setup]  [11:20:32:514] [Info] Started with 'install 2a5901f5be6545b39f551a92214978d6'.
[EAC Setup]  [11:20:42:522] [Info] Argument handling done, requested action: 1.
[EAC Setup]  [11:20:42:561] [Info] Operation 1 completed successfully.
So once Blue Mammoth Games roll out the EAC update for all players, there should be no issue continuing to play it on Linux with Proton.
How difficult is it then for developers to upgrade to a newer version of Easy Anti-Cheat to get the Proton support working for Linux players? Epic originally said it was "just a few clicks" but the reality is a little different. Developers need time to test it of course. When asked about it this developer said:
The steps are to upgrade to EOS SDK 1.17 (released September 23rd) and then enable a client module for Linux. I suspect you'll see more games with support over the next few months, especially with Steam Deck being Linux based. Most developers have longer patch timelines than we do.
All good news then, especially since Brawlhalla is a popular game that sits firmly in the top 100 on Steam.