Please, don’t tag the devs. They will get flooded with notifications.
ISO weeks begin on monday and end on Sunday. The first week of the year always contains Jan 4th. Sunday 2022-03-06 is the last day of week 9.
The locale version depends on where you are. In the US, the first day of the week is Sunday and the first week of the year is the one that contains Jan 1st. Sunday 2022-03-06 is the first day of week 11.