Sometimes the battery usage plot is getting cut off and doesn’t show all the data since the last charge. It basically shows only a few last minutes and the estimated remaining time.
It usually works for some time after the charge but then it randomly gets cut off:
This has already been mentioned in the Android 12 release topic:
This is a new one though:
And after a while:
Previously it at least showed more or less a complete list of usage. Now it manages to forget even that.
Yes, this is getting silly. I currently have:
The last charge reached 80%. I get the impression that has the effect of setting all battery usage info to 0.
There is a note, as shown in your screenshot, that usage is not measured when the phone is charging. I’ll have another look tomorrow if I remember.
I charge overnight so it always starts (or should start) at 100% for me. But the plot only shows data from 90% or even less. 
