I might be wrong here so, take this with a pinch of salt. It might be a bug, there are various reports of this on reddit, no real solution. But, here’s my potential thoughts…
Google wellbeing is tracking, your day and resets 12am daily.
It might be that Nothing screen on time widget is tracking from when the phone is taken off charge at 100% to when it is next charged which might be why there’s a 10 minute delta between the two.