MacBook Pro (16-inch, 2019) running Monterey (12.1) was working normally. I closed the lid and went out to do some yard work.
When I came back and opened it, the Dock is goofy. When the pointer gets close to the dock, the Dock slides off the screen. If I continue further down, when the cursor gets within a few pixels of the edge, the desktop background begins blinking black, normal, black.
I have never turned on hiding and I have not changed any preferences today or yesterday. Nor installed any software nor did an update. All is at the latest available version.
Nothing is in full-screen mode.