Battery draining fast

iPhone 11 and later models, battery performance --> About the battery and performance of iPhone 11 and later

I found this to be the case as well. What I noticed is for a few days after any power off and power on (restart), the battery will drain extremely fast, like 2-3x as fast as normal. After that period, it goes back to its normal rate of discharge for the settings I have selected. I think it must be doing a great deal of background work for the first few days after restart.

I first noticed this after an IOS update, but then realized, it was with any restart.