Minimized windows randomly re-appearing
I am experiencing a problem with my MacBook Pro running Big Sur - applications that I have minimized (by clicking the yellow button in the top left corner) will randomly re-appear. For instance, I may have several apps like Safari and Word minimized while reading a Preview .pdf document, then suddenly the top menu bar will flicker from black to light grey then back to black, and Safari and Word reappear behind Preview. This occurs even when I am not interacting with the keyboard or mouse.
MacBook Pro 15″, macOS 11.6