Savage fight progression changes?

I just wanna preface this that I started raiding at the very start of Pandaemonium so I might not know things.

As far as I know, whenever a savage fight is newly released, as long as you haven't cleared a floor for the first time, you can't get the next floor. Skipping is only possible for reclears, I think??

I've been unsub for a year and now back to challenge Arcadion Heavyweight Savage. I just finished M9S and was going to go in M10S in the Party Finder to take a look. I joined a fresh party that I thought was for M10S but it's actually M11S. I only knew it was M11S when the duty window popped up saying it's M11S and that I can't get weekly rewards for the previous floor because I skipped it. I was confused but still went in (It's Sat, there's no way I can clear M10S before the weekly reset).

My question is, did the rules changed or is this a bug that I should report? Or am I wrong in my assumption??

I think it's always been possible. I remember MrHappy saying he knows people who do it. Because obviously some people just want the mount from the last fight.

Obviously it could be considered sabotaging because you'll have less gear in M12S (unless you were extremely unlucky) but probably not gonna PF clear it on the first week anyway.

You've always been able to skip raids, you just forfeit their rewards for the week. Taxi groups are fairly common later into the tier for people who don't feel like reclearing earlier fights they don't need gear from. You just need one person who has cleared the previous one to take everyone else in.