It's probably about en Passant because ur opponent made a pawn move that made it move 2 squares, and if someones pawn moves 2 squares up and lands next to a pawn of urs u can en passant.
Idk how it works cuz i've never gotten an alert like that, but im assuming thats why.
yeah i know, im just saying because thats how an en passant move can be activated, thats why it gave u the tutorial? Maybe it's just bugged so that as soon as a pawn is moved up 2 squares it gives u that notification?
Anyhow if u go to the bottom left of the page and hover over "report a bug", click that and report it.
When I started a rapid game and my opponent played 1. e4, the screen popped up with the following message: Learn about this move - Do not show again. I clicked on it out of curiosity and it led me to a page about en passant. Is anyone else experiencing this bug?