To answer your question, it normally has to be the originating forum's minimod as they can only move stuff in their forum. But as I am the weird minimod/staff member I can move from any forum.

Well, the rollover from Sunday to Monday is definitely what I intended, but now I can see that the code I wrote was off by a day. It turns out that "midnight last Monday" in fact means the midnight that Monday ends on, and not the midnight that Monday starts on.

Fix deployed! Come this Sunday, it should roll over on midnight as I intended. Let's leave this bug report open until then so we can confirm.

locking up as resolved!