Taper weeks feel harder than increases weeks

I am in week 9 of my 18 week training, and for some reason the 3 taper week long runs I have had have felt way harder than the “longer” long runs. Anyone else experience this? I am taking about the same speed in the taper (actually a bit slower) than the weeks surrounding.

Fueling / hydration also consistent - no major changes.

I know every run feels different, but find it interesting that 3 separate taper weeks have felt really hard!