My system specs are 5950x 64GB RAM 4090 FE, and I game at 4k 144Hz. I run Ubisoft Connect through Lutris, with proton-cachyos-slr as the runner. All my games work after installed, AC4 Black Flag, Far Cry New Dawn, The Division 2, etc. When ever I open this game, I get a prompt with the header, FC_m64d3d12.dll, that says: A debugger was found running in your system. Please, unload it from memory and restart your program. I’ve tried disabling mangohud, Ubisoft overlay, read about split lock in the kernel, checked status, mine is off by default, I guess? All my games run through the one proton layer, so I can’t really change each games runner. Curious if anyone else has had this issue, thinking I may have to buy it on Steam.
The Steam version also uses Ubisoft Connect, but the game also has awful layers of DRM like Denuvo and VMProtect. So I don’t think it’s even possible to tell in what exact ways the Steam version and Ubisoft Connect version differ in that aspect.
Still, if you buy it on Steam, you’re not really going to evade anything as far as I know. Steam will create a new prefix, install Ubisoft Connect in it and I’m not sure what you’ve gained at that point other than spending money twice. But it’s possible that Steam and Ubisoft Connect DRM are coupled and set up in a way that it “just works”?
Nevertheless, you can absolutely change each game’s runner; try different Proton versions with the same prefix, that shouldn’t be an issue whatsoever. You can create individual entries for each game as well so you don’t have to keep switching.
However, I think this error could be directly related to those awful DRM layers. I would really try to install Ubisoft Connect a second time in its own, new prefix with no modifications and no other games, only Far Cry 6.
Please note these DRM layers only grant a limited number of installs and such nonsense. I would personally try to install Ubisoft Connect through Heroic Games Launcher since I’ve personally had more luck with it than Lutris but it’s up to you.
If I had the game I’d gladly try to make it work and tell you the solution if possible but alas, I don’t. I just wanted to inform you that you should be able to try different Proton variants and such and even try new prefixes before giving up.