Super Mario Maker/Super Mario Maker 2 content creator GrandPooBear is very well known among fans of the series. He's created some of the most unique and challenging stages either game offers. One of his most recent works was a low-gravity level that didn't use any exploits or glitches. Sadly, and without much reason, Nintendo has deleted the level.
GrandPooBear says the level was removed for “harmful or inappropriate content," but GrandPooBear has no idea what this is referring to. The level didn't feature anything inappropriate by any means, and there's simply no way for GrandPooBear to get more information and revise his course.
Hopefully GrandPooBear gets in contact with someone at Nintendo who can help him tweak the level for its return to Course World, but that seems extremely unlikely at this point. When your levels can be yanked at any moment, and seemingly done so without any truth to the reason given, it makes you worried about all of your creations being treated in the same way.