[2023] Сrashes when launching the game from the launcher [Linux]

That seems to be saying that library needs to be installed or updated. It wouldn't surprise me if CK3 needed a newer one than Stellaris.

error while loading shared libraries: libtinfo.so.6 (4368868)

Installing SAS 5.1 on Linux versions that do not have ncurses-lib version 6.x, such as RHEL 7.x produce the following error while executing 4368868 support.oneidentity.com
Does that help you?  

A CK3 patch does not change the launcher (they are separate apps with independent update processes), so I don't understand what's happened there. Indeed the launcher hasn't changed for about 2 weeks now, AND CK3 not for a week. Could that update you saw, have actually been a mod you are subscribed to?

But if you get the same error as above when running ./ck3 then that's nothing to do with the launcher. All I can suggest is seeking Linux help for how to obtain and install that package. Good luck!  

That's a great question and I don't have an answer. When Install this game - any game - in my Linux VM, all that comes down is a native Linux version. I don't have Proton though, could that be confusing Steam ?  

Hmmm. How about if you change your Steam download region?  

So we are back to the libtinfo.so.6 error. I don't see any alternative to you sourcing ncurses-lib from somewhere!  

There is absolutely something wrong with the game and/or Steam as they are on this machine, I completely agree. But I'm sure it is not a general bug in the game, or all Linux users (including myself) would get it.

The Windows version issue is particulaly bizarre. How Steam detect the OS and select the appropriate game version I have no idea!

I don't suppose you have access to a Ubuntu or SteamOS installation to test the game on?