Cadence problems with Kickr 5 / iPad / Zwift

Hi all,
I’ve noticed some kind of a problem with the cadence. Normally my cadence is between 80-90. The last few rides it was lower and some how “connected” to the speed.
As you can see in the picture, I was doing a workout with my normal cadence but it showed a cadence around 60, during the slow climb it dropped even to low 30 and came up to 70, 75 during the fast decent.
Any thoughts or advices?
Kickr 5, newest firmware 4.2.5
iPad iOS 15.1
Zwift 1.18.1

Cheers Jan