Comment 11 for bug 1746200

Grepping journalctl is case sensitive; so 'refind' could be logged with some uppercases, does not know, so watch 'journalctl -b' to find the exact spelling.

Mixing different DEs will only add confusion/conflict/headhache ...
Fightting about trouble works the other way: test step by step, the simpler the easiest.

Your report is about 'regression' pointing to a freeze on S3 recovery. Is it really the case ?
Then you said 'randomly', which is not the easiest case. About 'intel-microcode' that is used very early at boot time, i doubt it can be blamed (maybe glance at the mobo forum to know if other users are affected).

What can you do more: clean the system with gtkorphan & bleachbit (as root carefully), test ram/swap stress.