(
link) One of those times when the fine amount matches the official fine description, which is not always the case. It was a foul per the rule:
RULE 12 SECTION 2 ARTICLE 10. IMPERMISSIBLE USE OF THE HELMET (
link)
It is a foul if a player:
(a) lowers his head and makes forcible contact with his helmet against an opponent; or
(b) uses any part of his helmet or facemask to butt or make forcible contact to an opponent’s head or neck
These provisions do not prohibit incidental contact by the mask or the helmet in the course of a conventional tackle or block on an opponent.
Penalty: Loss of 15 yards. If the foul is by the defense, it is also an automatic first down. The player may be disqualified.
Video rulebook explanation (link)
Funny how the league office can review entire games and find infractions like this. However, they sometimes do not clarify something like the supposed 'football move' Jake Ferguson made leading to the fumble, requiring Trey Lance to take out the ballcarrier.
Whatever. I highly doubt Lance has ever tackled that many players to begin with. It is hard enough for defensive players to remember what to do in the moment.
The important thing is not allowing the opposing team to score, regardless what the score is at any given time of the game. It was a good play on Lance's part. Hopefully, he will not be put himself in that position again.