In a tweet, @Piece_of_Craft said that Nintendo had objected to his use of Mario in his Dreams project, and had called on Sony to pull his work offline. As such, his Mario projects -- used by many user-generated Super Mario levels -- are now on hold.

Good news and bad news

We flew too close to the sun boys! A big video game company who i will keep nameless obviously didn't read my "be cool" note in dreams

no worries though have a back up plan. But for now Mario projects in dreams are on hold until i put said plan into effect pic.twitter.com/ifGDM0jFZ3 — Piece of Craft (@Piece_of_Craft) March 20, 2020

It's no secret that Nintendo is fiercely protective of its intellectual property, although it's interesting that the company chose to pursue action via Sony, rather than approaching @Piece_of_Craft directly. Of course, Dreams does give players the opportunity to sell their work beyond the PS4, which opens up a whole new complicated avenue for potential copyright infringement, so Sony is clearly setting a firm precedent, going forward. So basically, you can dream big, but not too big.