What component of my computer might be damaged?

I am having some problems with my computer It started a while ago when a message apeared twicesaying that there was a problem with the GPU, I dismissed it but just now when i booted up the computer the boot procces was slow, There were some grafical glitches, the computer booted in safe mode and all the files were categorized as "other". I run a drive verification and it said the drive is funcioning normally then I run a permits verification and it said some files have different permits so then I run the reparation but nothing happened.

I suspect CPU overheating or a damaged SSD

I also have a time machine backup.

Update: I rebooted the computer and the problems were resolved but how can I stop this from happening again?