Update: 31/10/23 - The situation now appears to be fixed.
Farlight 84 is a hero-shooter battle royale from Farlight Games that currently has a Steam Deck Playable rating but it appears with the latest update, it's causing bans to happen like we saw previously with Apex Legends.
There's numerous posts filling up the Steam forum about issues with the latest update, and bans due to Easy Anti-Cheat certainly aren't the only complaint but if you were planning on playing some more Farlight 84 it's likely you're going to want to hold off on that until the situation is sorted.
Trying it myself today on desktop (Kubuntu 23.10) it didn't work at all. Loading the game just resulted in a black screen and then it eventually quit to my Steam Library, which I've also seen reported by others for some time. So even if you're not banned, you might not be able to play right now anyway. Testing on Steam Deck and it did work for me…but for how long?
I've reached out to Farlight Games to see if they will provide any statement or information on what's happening.
Farlight 84 is quite popular, with it regularly seeing somewhere around 15,000 to 17,000 players on at a time each day. So it would be good to see this issue solved promptly. If it doesn't get fixed, hopefully Valve will then remove the Playable Steam Deck rating before it causes other issues.