Hello Quickstep is using a lot of battery power in the background.
I’m using the Nova Launcher for now and hope you have another solution
It says 1h of foreground activity (with display on), that’s more than any other app. So you probably used it at some point after the last time you fully charged the phone. That’s probably the reason it drained 20%.
My Fairphone 6 drained 10% during the night at doing nothing… but I’m not sure Nova Launcher is better on this point