This feature is still on the backlog.
Don't forget to fix it in the Teams Mac app also!
109 votesJohn commented
The URL workaround (EN-UK or EN-AU) works fine in the browser, however the date format is still wrong in the Teams Mac app and there is no way to apply the workaround in the app.
The team continues to make progress on this. We will share more details as we have them.