mac mini 2014 keeps restarting, very slow

I have a 2014 mac mini running Big Sur 11.7.10.

Over the past couple years I have noticed that it is processing slowing when opening apps. I don't have a lot of heavy apps on the mini, use mostly apple based apps(ical,imessage, numbers etc).

From time to time I have had to reload the macOS when an update causes it to freeze or run very slow.

A couple days ago I opened the mini and while it loaded the screen went dark and the logo/progress bar appeared. The bar would fill half way and then freeze. After leaving it overnight, it was in the same position. I tried turning off, then on and same issue.

I did a disk utility, first aid, no issues. Reinstalled Big Sur, and now that I can get into the main screen, after a short period of time the screen goes black, get a message(pic attached), the logo and progress bar appears, loads and then back to login.

Is the machine done? Any idea what could be causing the constant shut down and reload?

Thank you.