That was a great level. I thought the difficulty was good for world 6 barring a few points that felt slightly unfair. A couple of those are listed below, as well as some other general bugs/concerns.
My first thought was not that this was an arrow cloud, but rather a place you could jump to warp somewhere. Sure, I guess it would make logical sense given that there an unreachable flower right before this, but surely there is some way you can make this a little more obvious and/or less likely that the player is going to jump down to their death?
Going left on this penguin is easy enough, but I found I got stuck on the bricks going back to the right. Perhaps you could make the column two tiles instead of three?
It's possible to bypass the switch entirely by jumping off the red platform while it's rising. See if you can move that line guide or stone box around a bit to ensure that the player absolutely HAS to use the switch to get the red coins.
I found this part a bit unfair. Naturally, the player is going to run along with the rock over the dirt, but this results in them falling to their death. Even as a veteran YI player/hacker, I forgot about this detail until I died. I think a good solution to "train" the player would be to put the Chomp Rock on a dirt ledge that you have to roll it off of so that they can see how the mechanics actually work.
The other melons were slightly visible at the top of their respective trees, but this one was completely obscured. I had to guess by randomly licking to stumble upon it.
It's actually possible to jump up here and get stuck. Try raising the platform by a tile.
Overall, this is a strong level with many alternate pathways and an interesting theme. I missed a flower and two red coins, so I'm curious to know where those may have been. Otherwise, it was a lot of fun and I hope you'll show interest in designing another level as well
(one happens to be open right now!
it literally filled while I was making this post, but if you ARE in fact interested, I'll send a message your way when another one opens up.)