Problem breathing after 4 hours use using p30i

My ahi count is reasonable- under 1 ahi most nights but right around hour 4 I wake up having breathing difficulty and end up taking mask off.
I also tape mouth.
My sense is that either the air feels too warm or pressure has changed. It’s set for 6 but sometimes reaches 7 or a bit higher. Always wake foggy brained and the feeling lingers for a couple of hours before settling into ‘something’less so but I almost never feel like before I developed SA.