Playoff incentive bonuses are treated like NLTBE and paid after the playoffs. They then are calculated into the following years cap using
the Adjustment clause. At the end of the season all LTBE and NLTBE bonuses are added and subtracted to whatever rollover is left.
Which means if a player has a LTBE bonus (which is part of the season cap hit) and doesn't earn it, the extra money if rolled over.
Opposite if an NLTBE bonus is earned.
Spotrac shows the + or - Adjustment ever year. At the start of this year the Bills had $856k added to their cap.
https://www.spotrac.com/nfl/buffalo-bills/cap/