what does a question mark in the notation side of a game mean?

For the notation of my #5 move, an en passant, there is a question mark. Does that signify anything?

Why didn't you press it and find out?

It was put there to alert you to a help topic about the en passant move. Every day, people write to the forum or to support@chess.com claiming to be the victim of cheating because they don't know the rules.

I believe the question mark was put there to cut down on the incessant questions.

Back to the drawing board.

https://www.chess.com/forum/view/off-topic/lets-get-it-straight-en-passant-isnt-cheating-49803184

There is also a question mark in front of the link to the Help pages. 

   I was under the impression that a ? after a move indicates that the move was a mistake. Double ??'s indicate a blunder,and e.p. indicates pxp under the en passant rule.                                                                           Okay, now I noticed that its a ? INSIDE A BLACK CIRCLE,distinguishing it from a plain  ? which would mean a bad move was just made. Utter nonsense.