If you want to compare Manjaro with Arch you should switch to the unstable branch and update both systems at the same time and redo your tests. Switching Branches - Manjaro Outdated packages may create different results …
Personally I’m working on the not yet released Manjaro Gaming Edition and had so far no crashes with games I tested it with. That OS will be launched with the Development | Q&A | Zotac Gaming ZONE and Development | Q&A | OrangePi Neo-01 most likely end of Q3-2025. Gaming is done via Gamescope similar to SteamOS.
I checked how it will work with the unstable branch, but the game Once Human still crashes after launch. And I don’t understand why on Archlinux with the same launch settings, with the same drivers the game does not crash. Video of the game launch process on Manjaro
If the games mentioned are Windows based (WINE) then this might be related; follow the links to learn more.
Additionally, and if I understand the gist of a few articles I’ve read lately, Lutris seems to have better handling of WINE internally, and might potentially allow a smoother experience.
Perhaps @omano might like to comment further, as my knowledge of Lutris is limited.