I don't play on my iPod that much, so I don't know if this happens in regular games. Anyway, I was playing in a custom-position daily tournament, and upon playing the checkmating move, it displayed it as a check. My Android doesn't do that, so I thought it was a little weird. So I play it and hit confirm because, checkmate, and it said I won. After winning, it still displayed as a check. I jumped on my computer, and it agrees that I played a checkmate, but the app chooses to use the check symbol. I am using version 3.9.25 and the link to the game is https://www.chess.com/game/daily/368924161 .
When choosing:
After confirming: