If you throw out the exceptional play of Burrow and Chase, the tactical mistakes of the Chiefs, and Mahomes having a bad day it really comes down to the two fundamentals. Blocking and tackling.
Watching the game with an unimpassioned view I see the difference in the Chiefs not winning in their inability to block the Bengals defense and to effectively tackle the Bengal's offense at first contact.
When the Chiefs did well on offense it was because of excellent execution.
When the Bengals did well on offense it was because of missed tackles.
Best tackle of the day might have been Kelce in OT after the interception.
We can always Monday morning QB the individual plays but the constant in this game was failed blocking and tackling by the Chiefs.