20 days ago - AndrewT - Direct link
I was going to suggest you lodge a bug report about this, but unfortunately you can't because the only supported distro for this game is Ubuntu - QA will not accept any reports on Arch or any other one.

Odd that this happens with an older game CK2 and a newer game Stellaris but not the game in the middle EU4. CSL and SuMa are not our games (we just publish them) and they use completely different game engines (to each other and to our games).

The fact that the OS keeps the game's resolution is a problem, no doubt! Aside from some scripting in Linux I can't think of a way of preventing of fixing that.

Are you on the latest AMD driver? The latest Mesa version?  
19 days ago - AndrewT - Direct link
Condex said: I've also tested the "Borderless Window", but under my impression, it's exactly the same as running in Fullscreen, but with another name xD
It will certainly look exactly like fullScreen, but it is more like windowed mode under the covers. Indeed games are starting to come out now with no fullScreen mode at all, only borderless and windowed (eg CK3).

Condex said: Nevertheless, if you have a recommendation on that "scripting" solution, I'm all ears
Way out of my wheelhouse I'm afraid! I know nothing about such things. You might check with any Arch support resources there are.