This has to be definitely Serious Foul Play or definitely DOGSO. What it cannot be is a bit of both so that adds up to a red card.
Painful that it was, I am not convinced on Serious Foul Play. Just because the defender made a (horrendous) mistake that does not mean he cannot try and recover the ball. He did nick the ball but then caught Vardy with his follow through. Is there a difference from the case of the West Ham player who cleared the ball, caught the opponent, got a VAR inspired red card and then successfully appealed?
DOGSO is equally doubtful for me - the keeper was slight favourite.
Its a yellow for me - but arguable up to a red (unlike the West Ham one!).