Hey this is a fun game! The art, music, and sound effects suit each other really well.
Maybe there is a frame-rate issue with the jump? I think it should be possible to jump here in stage 5:
(It was also not possible for me to reach any platform in stage 4 but I could beat it by waiting for the bunnies)
I usually encounter this type of issue when the main loop is executed at render/compute speed instead of fixed time steps, computers with different speeds will end up jumping or moving at different heights.
Great job on this game though, this is a really successful jam game (*/ω＼)ノ”