On android its actually weirdly difficult to tell what apps are or are not causing battery drain, especially on Android 8 and newer (android 7.11 had the best battery usage graph of any android version, it would even show all of the "wake time" in comparison to screen time so it was very easy to tell if it was doing stuff in the background a lot) My understanding is that if the apps are going through the Google Play Services APIs to do stuff it won't show up on your battery usage graphs.

It also doesn't help that the square button just shows you the "recent apps screen" where it shows apps which you've used recently in chronological order and may or may not have a state saved in memory/swap and may or may not currently be running in the background.

So basically, Android annoyingly just does stuff and you have to trust it. And if you're getting extra battery drain, seriously try Safemode and see if it drains noticeably slower in Safemode. Or factory reset and be slow about reinstalling apps to see if you notice a change when one gets installed