“Why is my weekly meeting suddenly an hour off?” Because the US, Europe, and much of the Southern Hemisphere change clocks on different dates. Enter a recurring meeting and the attendees’ cities to see every week it moves for someone, before it happens.
Uses your browser’s built-in time-zone database (no network). Calendar apps anchor a recurring event to the organiser’s zone, so attendees elsewhere see it move. Highlighted weeks are the changes. Governments occasionally change DST rules at short notice; keep your browser updated.