iPhone 6s plus battery, from 100%-5% 7hr standby + 1hr screen on. Is it a battery problem?

My iPhone is 23 month since purchase.

The battery has been very good until ios11 update, which i remember during update, the back of my phone was pretty hot. I have feeling the heatup somehow damaged the battery.

Since then, the battery has been draining faster than usual.

But this is the latest battery summary (screenshots):

Total screen on time was less than an hour, and when i got home it was at 1%! When i took the screen shots i already charged it a bit.

Still i think is crazy a 10 minute on a beauty camera app would take nearly 30% battery, 14minute on iOS camera took20%.

I charge my phone only when free but never overnight, most of my app's background refresh is off.

Is this rate of battery deterioration even normal? And does this mean the Battery Health Beta is completely inaccurate (apparently my battery health is 85%)?