What are the most-facepalmish errors that an elite chess player has ever made in a real tournament?

Even professional NFL, NBA, soccer players, etc. sometimes make absolute facepalming errors in a game (example: Kirk Cousins taking a knee deep in Eagles territory at the end of the first half when he was supposed to spike the ball, the Vikings player who picked up a fumble and ran the wrong way, etc.).

I was wondering if there are any equivalents in chess. Has there, for instance, ever been a grandmaster or even just an elite pro in chess who did something like leaving their queen blatantly vulnerable to capture (in a way that wasn’t part of some hidden stratagem,) etc.?

1893, Steinitz vs. Chigorin.

I am a total amateur when it comes to chess, but even I could tell from the diagram that White moving its bishop in that situation was a particularly dumbass move, especially in the 23rd game of a match.

There was a case a decade or so ago where a human playing a computer managed to completely overlook a mate-in-one position. I’m not sure I remember enough details to be able to find it, though.

I saw a video of a high-level game a while back in which Magnus Carlsen moved his rook to an unprotected square where it could be captured by a bishop. It wasn’t a sacrifice or a positional gambit – he just plain forgot about the bishop. He fought on for a few moves but soon resigned.

Found it! There's a Bishop There?? - YouTube

These guys play thousands of games a year. They’re bound to screw up every once in a while.

@Chronos You’re probably thinking of game 2 in the Deep Fritz v, Kramnik match:
Blunder (chess) - Wikipedia