I think I’m going to stop playing that Alchemy Stars game on my phone and put it on my iPad Mini 5 for a week or two and see what the battery difference is but since the iPad is still on iPadOS 14 it won’t really be comparable anyway. I definitely noticed a drop before I started playing that game though, iOS 15 is just really good at draining the battery but that’s expected for a beta to some extent.
I am still happy with my 12 Pro Max compared to the 3-3 1/2 hours my XS Max that it replaced, I just miss those 11+ hour screen times lol.
I only charge my phone with my 12W iPad charger but since the battery is degrading anyway I might as well get the rapid charger back out.
All of my apps were behaving with respect to screen off usage until 15 DB3 but it has been an issue on DB4 too.
I am still happy with my 12 Pro Max compared to the 3-3 1/2 hours my XS Max that it replaced, I just miss those 11+ hour screen times lol.
I only charge my phone with my 12W iPad charger but since the battery is degrading anyway I might as well get the rapid charger back out.

All of my apps were behaving with respect to screen off usage until 15 DB3 but it has been an issue on DB4 too.