Incomprehensible Battery Drain

[Reggaenald]

The screenshots say it all.
At first I was confused about Lockdown‘s background activity despite the app having been closed and no connections being active.
I decided to just delete the app for the time being.
But without it, it’s at least as bad.
How? Hard resetting doesn’t do anything.
I’m running 17.0.3.

 

[Reggaenald]

Just noticed that YouTube apparently was active in the background all day long. Even though I don’t have the app installed and use the website in Safari.
How??