I need a Flatpak Wurm Online
To try and fix the stuttering. Perhaps something isn’t the right version in Manjaro. Can you run games in Docker? Then you can make a Ubuntu docker, and run it in that. Perhaps it was tested in Ubuntu.
You might be able to specify versions of dependencies with Flatpak. That might be a lot of work to try and fix the annoying ass stuttering.
Perhaps just use Docker and the distro they tested it with.