Hmm, I was about to make a post that's similar to yours. I'm currently using CCC to backup my 2TB nvme system drive to a 2TB HDD on my old old MacBook Pro (the last of the non-retinas, 2012) because I'm worried about corruption (I can boot to Safe Mode and Recovery, but I can't seem to get to a point where no errors are reported by diskutil / Disk Utility)
Last night when the problem happened, it wasn't getting past the (verbose) boot process and while I can't be sure, the WindowServer errors you mention definitely look familiar. So I swore loudly, slammed my desk and decided that both of us needed to cool down. Of course today, it actually gets to the login screen but very quickly grinds to a near-halt (near because often the caret will keep flashing ?!). I've been playing GTAV remastered on my Windows nvme drive while the backup takes place and just generally trying to stress the system, because at one point i thought it was my hand-me-down graphics card that had finally given up the ghost, but I haven't had a single issue on Windows. In fact, it's reminded me of how much I used to enjoy playing games haha.
So yeah I'm just waiting while my macOS nvme backs up - I don't want to lose the entirety of my only entire local copy of my iCloud Drive, because I'm anticipating having an "internet break" (i.e. I couldn't pay my bills and stupidly joined my mobile bills up with my broadband) any day now so I really want to be able to access all my stuff for what might end up being a permanent disconnection. Meh, I think it will probably do wonders for my mental health. I used to place so much importance in technology, along with music it has formed basically all of my identity for the last 20 years. Perhaps it's time to go out and see how good the graphics and gameplay are in reality.
If it helps, my advice to you TRH is if those apps and settings are important to you, try and get your drive backed up. Then I guess the next thing I'll try ... well, I'm not sure tbh. Update my USB OpenCore installer (oh wow, that's a point, better redownload the 12.4 installer! Thanks for reminding me) Reinstall macOS and then drop in my User folder ... hmmm. But why do I get the feeling that backup will complete without any errors, the Windows stress test will keep on chugging without any errors, and then I'll be back at the WHAT THE HELL IS GOING ON HERE stage shortly..
I suppose I've had months of problem free (I suppose if you don't count the "Hash mismatch" error - ooooohhhh, wait... the HASH MISMATCH ERROR THAT I WAS IGNORING BECAUSE I THOUGHT IT WAS RELATED TO IT BEING A HACKINTOSH... maybe it really was filesystem corruption? In which case, excepting it being an actual hardware fault with my precious precious 2TB nvme stick - which I hope is still under warranty - reformatting and reinstalling will actually fix the issue?
Sorry for the interminable drivelling, especially as I have nothing helpful to say except #metoo. Unless you weren't considering a backup, in which case that's useful advice.
I will come back and update in a few hours probably, that's unless the internet chop happens tonight.
