The thumbnail shows the common form of smothered mate with the king in the corner. The Wikipedia page has other forms - like in openings. A grandmaster getting a smothered mate (even in a speed chess game) is uncommon because what the attacker is up to tends to be obvious. The thumbnail form done by not one but two knights must be exceeding rare. I'd never seen it before.
Magnus had a big advantage and after 25...Nxd3 white mentally collapsed. He spent ~30 seconds thinking which is a vast expanse of time in speed chess, he made a bad move, he made another bad move, and then Magnus had mate in 3.
https://www.chess.com/analysis/game/live/116721637783?tab=analysis&move=49
In chess, a smothered mate is a checkmate delivered by a knight in which the mated king is unable to move because it is completely surrounded (or smothered) by its own pieces, which a knight can jump over.
The mate is usually seen in a corner of the board, since only three pieces are needed to surround the king there, less than anywhere else.
