If you're mixing a dedicated GPU and onboard graphics you need to set the dedicated GPU as primary somewhere, otherwise all screens get rendered on the onboard and "reverse PRIME'd" to the dedi GPU outputs.
I'll see if I can find the snippet that fixed this for me.
We use gitlab ultimate at my work, I'm the main admin of the instance. Like 2 weeks ago when there was the cvss 10 vuln, gitlab sent us a .patch file to apply to the instance instead of releasing a new minor cause they didn't wanna make the vuln public yet. I guess that's coordinated disclosure, but I still found that remarkably jank.