In all 3 of Tom Brady's Super Bowl losses, he had a chance to win.
In both of Patrick Mahomes Super Bowl losses, the Chiefs were blown out. In Super Bowl 55, the Chiefs did not even score a touchdown & lost by 22. In Super Bowl 59, the Chiefs were down by as many as 34. Tom Brady was never held out of the endzone in his Super Bowl appearances.
Brady is 2-0 vs Patrick Mahomes in the playoffs. Case closed.