To me, this has been a rolling trend since reopening. Options are thin/availability really tough further out, but then in the weeks leading up to the dates in question options start to open up. People are booking placeholder trips and then figuring out their travel tolerances later on at a large scale, in my opinion. A lot of folks have circled 10/1+ for the anniversary and made reservations a really long time ago. As folks are finalizing their plans now with a clearer picture of offerings, rules, virus trends, etc, you see a lot of shuffling around.
But it’s not just 10/1. I’m a habitual resort changer and I’ve watched the same trend for my May trip, my July trip, and just this past weekend.