Random floating small squares on screen

If that is either in the Finder or any app (as in: present all/most of the time), then it appears to be a hardware/graphics problem; you need to start a ticket using the Contact Support link in the upper right corner of this page.

Sounds like a GPU problem, shut it down & let it cool, restart & see if they reappear.

I have never heard of floating anything on a screen - could you capture a screenshot and post it please.