Not sure where you are getting your numbers. Looking at 2020, UCF went 6-4, and averaged 48.5 PPG against teams without a winning record, and against teams with a winning record, they averaged 32.5 PPG. Back in 2018, they managed 45 PPG against teams without a winning record, and 41 PPG against teams with a winning record.
So yeah, Heupel's offense is pretty consistent when facing off against bad teams, that's what I've been saying, but as he gets farther into his own recruiting cycles, the offensive production starts dropping off against teams with winning records.