This is a longstanding IT issue and has been posted many a time on this board, it's not hard to find via search. Here's one of many examples that I happened to answer years ago
CANCELLATION POLICY modified by Marriott/Hotel

There's no conspiracy here, it's just incompetence. This is especially common in a case like OP's where they booked a year out.

Of course, there are cases where hotels intended to make things nonrefundable due to seasonal events, etc, and try to change the deal after the fact. But that's a tiny fraction of cases and it's far more common to see more mundane inconsistencies like the number of days in advance you have to cancel changing from 1 to 3 or something.