The decline in Mahomes' TD pass yardage probably means that other teams adjusted to the Chiefs' deep passing game to take it away. That became easier in 2022 since Tyreek was not there.
If you play a 2 high safety shell with a light box (as the Bills have done for the past several seasons) to take away the deep ball, the Chiefs have adjusted. Their running game was better in 2022 especially against a light box and they likely threw more short to medium passes.
As others have said, teams adjusted to Josh by taking away the deep ball. At the beginning of last year Josh was taking the short to medium throws. At some point he started playing hero ball and taking deep shots. Any thoughts on why he changed?
In any event, I hope and expect that Josh will learn patience and stick with it. If we can improve our running game that will help open things up for run-pass options and play action passes.