Also the logbook:
OS region settings:
This has been discussed many times before and still the issue persists. Please just add a config in the user settings so we can manually change it in case the detection is incorrect (for me it has never been correct since I’ve started using HA).
And a configurable first day of the week, in pretty much all of Europe we use Monday as the first day, not silly Sunday and still I get the following date picker with Sunday as the first day in the Logbook tab: