I had similar behavior caused by file corruption, and what I believe was a faulty SD card. Also on an RPi. Thankfully I had most of my services and configs backed up and on another disk.

I was also digging through system journals and log files, tracking down what the heck was failing. Eventually I found some system files which were corrupted, and re flashed the SD. Ended up happening a couple times before I replaced it.

Gravy’s a process. Too think? Add a little more liquid. Too thin? Add a little more flour (or even a cornstarch slurry)