A strange bar at the top of my screen is obscuring my game.
it seems to take a certain part of a frame and projects it over the game display itself, as shown that it actively blocks the f3 debug screen.
I don't know what caused it, it didn't appear during any special activity, or something particularly draining for my computer.
I encountered the bug in 1.18.1, and opened the game in other versions to see if it persisted; It appears in all installed versions from and above 1.17 for me, both modded and vanilla.

Note: I can make it disappear by entering and exiting fullscreen with the aid of the f11 key. But even though it is easily fixable for me, it shouldn't be there in the first place.