Crazy penalty in KC.
The Chiefs threw for a big first down with nine seconds left. The Chiefs were going to call their last timeout to stop the clock, but there had been a penalty on the play. Myles Garrett was offsides, and the Chiefs declined the penalty. The Chiefs then lined up and as soon as the refs started the play clock, Mahomes spiked the ball. Another flag is thrown.
The declined penalty had stopped the clock, so Mahomes spiking it while the clock was stopped is intentional grounding.
I had never heard of that wrinkle to the intentional grounding rule.