Welcome to SMWC, and please stick around.
I'll admit, it's a long time since I've seen a level like this, and it felt pretty nostalgic. I was looking for that bonus room, haha. I'm glad to see there was a way back into the main level. I just didn't expect you to use it for a Dragon Coin.
My main concern with the level is no "Vertical Scroll at Will" since there's a lot of stuff you can bump into above the camera, some of which you do need to interact with. There are also times Mario needs to go above the camera. I think this is a pretty critical thing to enable before your level can really be assessed fairly. The level has clear conceptual unification and gets continually harder as it pushes Lotuses. It is challenging in that movement is constant around obstacles and munchers on the swooping platform. However, it may suffer a bit for being repetitive in respect to its length.
I could also not get that box with a one-tile gap beneath it, and I don't even want to know what's in there at this point. I just hope it's one single coin so I wouldn't have to die 100 times to find that out the hard way.
One major issue you may not have stumbled upon in your play testing is underneath the diagonal pipe: if you walk under it, you are killed instantly. There is a weird behavior associated with it that gets hidden in SMW by setting up a thin pipe right under the edge and it extends all the way down so you don't accidentally die.
There are some Kaizo concepts in this level, such as low-ceiling jumps with a tile of leeway next to a threat. The Volcano Lotuses can be killer to deal with since their placement can put the fireballs very close together and above the field of view. That said, I don't think the level is "Kaizo-hard" and might still be scored in the contest if posted in the sticky? I dunno, I don't consider myself good at Kaizo but with some effort I could beat this. The level probably won't fare too well visually with the chop shop bonus room, green bleeding into the dirt, blackened grass, and other disconnected ground near the end, but that's just a ten point category. I think the level would be stronger without the bonus room or with a restructured, neatened bonus room (sadly, the neverending bonus room is my feel-good chill zone) and a bit more palette and object-connectivity touch-up. Consider extending the level and integrating different styles of obstacles requiring different maneuvers with the swooping platforms. It is fairly setup-based so you should be able to move chunks of the level that are already established without breaking continuity if you find your new additions are easier than what comes near the original end.
Just look above you...
If it's something that can be stopped, then just try to stop it!