ok I did find two ‘known’ knowns with no solutions here. one below
this is about restoring a disappearing ‘suspend’ button the menu but you may find the edits in the ./conf files interesting:
a search for ‘intermittent’ turned up nothing. a search for ‘intermittent shutdown’ returned nothing. But chase the cinnamon/github link in the first source. It’s common, it happens to people, but not seeing a lot fixes either.
someone else here will have the answer in an hour I’m sure.
I am just spitballing above my pay grade-- good luck.