For the last 2 years or so, when I set a due date on a Trello card, the first day of the week has been Sunday, not Monday. This is what I want. A few days ago, something changed, and now the start day of the week is Monday, not Sunday. This is not what I want. The guidance at
https://support.atlassian.com/trello/docs/turning-on-international-timedate-formatting/
is not accurate. My language is set to English (US), and yet the start day of the week is Monday. I have switched from English (US) to English (UK) with no change in start day; I have switched back, with no change.