I tested it again and made a video. If you need more just let me know :)
(the jumping itself doen't seem to be the problem)
Yeah, that's what I thought. It's not a bug, it's a little quirk on how collision checking for hazard blocks work.It thinks you're on the floors since... well... you're on the floor. But the center of the player is inside of the block already.
I'll think on solution for that.
Thank you :)