I was experiencing similar issues under Manjaro. I couldn't tell exactly when it happened but attributed it to a kernel or other update.
Are you seeing anything in dmesg? I was seeing kernel ring timeouts just after booting (I don't know how it recorded them from before the freeze but it did). My searches led me to find that the Ryzen 5600 silicon had degraded just enough to be unstable. I could underclock it and it got a bit better but not fixed. In the end I replaced it with a new 5800 and the issues completely went away.
It would be nice to have a much more aggressive anti-bot stance for communities/content that aren't local. If google or any other crawler wants to crawl c/lemmy@lemmy.ml then it should do it on the source instance. Doing it on mine makes no sense.