iPAD Pro 11" 2018 battery issue after 13.5.1

I updated the iPad Pro to 13.5.1 on 6/12 and charged it to 100%.

I then turned the iPad off (completely powered off) and put it away.

I turned it on today only to find the battery completely drained. This never happened before. Worked perfectly fine before the 13.5.1 update.

I have another iPad Pro 10.5" that I updated to 13.5.1 on the same day and also turned off in the same manner. Turned on today it has 100% charge.

I downloaded a battery app onto the problematic iPad and it tells me that the charge capacity is 7812 mAh, which is per specs the full capacity.

I recharged it fully and it seems to be loosing 1% of capacity per 2-3 minutes of screen use (just open screen with Settings on, no intensive apps being used).

This seems like a software issue to me.

Any ideas on what I should do?

Settings on the problematic iPad Pro are the same as on the nonproblematic one, no difference in background updates, apps on it and the like.