Constant crashing with FCP, even when it starts up

I am experiencing a recurring issue with FCP that has been getting worse and worse with time. I will be working and either I try to do something with the timeline and when I PLAY it will only play a few frames before freezing (audio keeps playing though) or I drag an effect on a clip and it gives me a warning about how it can't be done, no more info is available... even standard built-in Apple effects like Gaussian Blur. I quit FCP because it won't work until I restart it. Sometimes it will crash... just completely disappear. Every time I try to start it it will appear for a second or two and then disappear again. This will happen multiple times a day as I'm editing.

Mac Studio M1 Ultra 64GB o' RAM

Library running on WD_BLACK SN850X 4TB NVMe SSD inside Acasis enclosure via Thunderbolt 4

FCP 11, though this affected 10.8.x as well

Mac OS 15.1.1, though this affected me in Mac OS 14 as well.

Here's what I have tried:

-DELETING PREFERENCES - This works. For a while. Maybe 45 minutes if I'm lucky.

-RESTORING PREFERENCES with PREFERENCE MANAGER - This does not work. I restore them and FCP will still crash right away, even though the preferences that were saved with Preference Manager were super clean after I had just set them up, before I used FCP in any way. If I delete the "settings" by holding OPTION at startup, go through the song and dance of dismissing the iPad FCP thing (why is that there?) and dismissing the plug-ins that don't work (that I have zero clue how to remove), I can then quit FCP, restore the preferences with Preference Manager and it works. Again for about 45 minutes of editing if I'm lucky.

-ETRE CHECK - No major issues found other than a few unsigned things like my Logitech mouse software (reinstalled that anyway). Also I have automatic security updates off and it didn't like that. There was other nonsense like "No time machine backup" which would have zero influence on FCP crashing.

-MALWAREBYTES - Scanned with the latest version. All clean.

-REINSTALLING FCP FROM THE APP STORE - Makes no difference.

-Don't have CHROME.

Obviously it has something to do with the preferences, but something outside of what Preference Manager saves and restores. Only fully deleting the preferences with the built-in method will fix it for a while. I could have some bad plugins maybe. I'd like to go through one by one to remove some of them but again I don't know where they are and I don't have uninstallers for them all. So I guess my first question would be is... what does resetting FCP do besides delete the preferences that Preference Manager backs up? Whatever that is, is my issue.