Whole screen glitched after updating

I patched a 2011 iMac to Sequoia a few weeks ago, and it was working fine up until today when I tried to install a software update. Once the update finished, I got a prompt from opencore to update the root patch (whatever that means), so I did. But as soon as it restarted, everything went to shit as seen in this photo. It still boots up and I can sort of make out the ui, but it’s completely unusable now with all the artifacting. I’m not knowledgeable enough to understand what went wrong. Can anyone help me?