You could try adding the __GL_THREADED_OPTIMIZATION=1 environment variable to the custom launch options, it improved performance and lessened bugyness for me.
You could also try to run the launcher with software rendering^1^ by editing ~/.paradoxlauncher/launcher-v2.2024.1/Paradox Launcher (you might have to change the version). Try adding –disable-gpu in the last line, between –no-sandbox and “$@”
You could also try disabling gamemoderun. It hasn’t really improved performance in my experience, but has caused some bugs for me. It also muddies the logs.