The usage figures in the window were coming from somewhere other than the ones in the menu bar.
The menu bar asks each account directly. The window read the history file Claude writes while it runs, which only updates while that Claude is open — so a profile you hadn't opened in days showed figures from before its weekly reset. Here that meant one account reading 92% of a week in the window and 30% in the menu bar, at the same time, on the same screen.
Both windows now show the same figure the menu bar does: live where that account's login is readable, falling back to the same history file underneath, and the note above the bars says which of the two answered. Start Session in a window also drops the reading it has just made wrong, which only the dropdown was doing before.
Existing copies update themselves within the hour.