Here’s a harmless tooltip showing the URL behind a text link:
Picture 1.pdf (22 KB)
Here’s the same tooltip still hovering over a different window in a different app (Safari, but it happens with others as well) in a different Space:
Picture 2.pdf (19.6 KB)
The only way to get the tooltip to go away is to head back to original Scrivener Space & window & move the cursor away or click elsewhere in the document.
Bet it’s an Apple bug.