Light dims in seconds, instead of 20 minutes

And maybe post a screenie of the flows here.

I use Homey in the same way, When motion is detected I turn on the lights and a delayed card to turn them off again. I do this after 60 seconds because the wireless PIR only detects motion again after 60 seconds. So it is no use to turn them off earlier for me or I would stand in the dark.

Please give us more details about the motion sensors used, and the flow you are using.
Perhaps we can figure out what is going wrong.