I am 95% sure that you used to be able to click the left side of the toast shown when you hid the Figma UI in a prototype in order to dismiss that toast immediately. Within the last few months it changed so if you hover the cursor over that area you get a text tool and clicking allows you to select that text (why would I want to do that?).
The toast hangs out on screen for ten whole seconds before going away. I’ll often have to do a series of screen recordings of separate prototypes and having to repeatedly wait for that toast to dismiss gets old in a hurry.
At the very least being able to select text elements of the Figma UI is a bug.