half of them would simply not open at all with any tweaking. The rest of the games eventually started to run but some of them were hit by performance degradation severe enough to not be playable.

It sounds like your video card driver stopped working and it's fallen back to non-accelerated graphics.

A recent update renamed the Proton packages.

Check your Steam settings (like the global ones, not specific to a game) and the Compatibility settings. In my case the selected compatibility layer was blank after the package rename.

Reselect whatever compatibility package you like.

I didn't have any issues after updating, have you tried using Proton GE instead of proton cachyos? That one is often more stable.

I used to have similar problems with Lutris. I have since switched to Heroic. You could try setting up one or two games in Heroic. Just point it to the same prefix and executable as in Lutris and see if it runs there.

Regression aren't fun. To solve them, you need to do proper debugging.

First, take a look into logs. See the Proton readme on Proton logs, and Arch wiki's article of journalctl on system logs. Also games have their own logs. When you have found a suspicious error, copy-paste it to your favorite search engine. Eg. Steam prints errors about game overlay on each start, and those are harmless.

Another option is to take a look into the issue tracker to see, if someone else has the same issue and found a workaround.

Third method is regression testing. It means going back to a working version, and testing each update to find out which one introduces the bug.

If these sound like a lot of work, it's because they are. That's why people often try random stuff that may fix the issue, or break your system, instead doing proper debugging. I personally don't have time for it, so I have given up running rolling release distros.

I hope someone is able to give you the actual fix for your issue.

I used Lutris on OpenSUSE Tumbleweed, but I haven't used it since switching to CachyOS; it just didn't work properly for me, and I haven't cared enough to troubleshoot it when alternatives exist.

What GPU? What CPU? If you are using KDE what does kinfocenter say about the version you are using, and X11 or Wayland?

Is that around when proton went from 10 to 11? I used proton plus to manually install the last version of 10 for games that had issues with 11.

Forget Lutris, it's been having a ton of issues lately. The lead developer also started using AI-generated code around the time (and being a real dick about it), but that might just be a coincidence.

Faugus Launcher is my preference. It handles Proton installations on its own without having to install system packages.

• update your system

• delete your game's wineprefix, it'll regenerate and may fix issues from changing versions

• lutris is not likely the issue unless you're using its runtime and something is clashing with it. With proton-cachyos-slr, you should have lutris runtime disabled and prefer system libraries enabled. See here: https://wiki.cachyos.org/configuration/gaming/

• wild guess, but new versions of proton-cachyos use ntsync by default which requires a kernel module that may not exist in your older system. I'm not sure if it falls back to fsync in this case, but that could cause issues. System update fixes this.

• if you're on wayland and using PROTON_USE_WAYLAND, the change to proton 11 may have broken some games. These typically would be crashes / white screens rather than lag. In this case you can disable PROTON_USE_WAYLAND or use the older proton 10 based version of proton

We're lacking some critical information like what's your GPU and which drivers are you using for it. But reading some of the replies you gave in the other thread I think it's fair to tell you that you should probably consider moving away from CachyOS, it is based on Arch and it expects you to update frequently, not updating for a while can cause issues because I'd the instability of the system, that is to say because things might get multiple updates in the meantime and not being able to migrate properly if you skipped the in-between. Also Arch expects you to read the news one possibly important news came from December: https://archlinux.org/news/nvidia-590-driver-drops-pascal-support-main-packages-switch-to-open-kernel-modules/ if your card is on that list and you're using that driver this might be it, Cachy might be running behind Arch on updates so you might have hit this now instead of in December.

This is why I dislike CachyOS being recommended to new users, it might be easier to setup, but it's still Arch, and it still expects you to interact with it as if it were Arch. Something like Mint or Pop might be better if you expect to go over long periods without update and don't need the latest versions of everything.