Patch 1.10 for Super Mario Maker 2 has been released. This is the first big patch since the game’s release. The biggest new feature is being able to play Multiplayer VS and Co-op online with your friends. There’s also a bunch of smaller features added, such extra tabs on your profile for First Clears and World Records, and a list of official Nintendo makers.
You can read Nintendo’s official patch notes on their site for the “full” list of changes. “Full” is in quotation marks because they have a catch-all line that says “Other issues have been fixed to make for a more pleasant gaming experience”, which basically means they fixed a ton of bugs, but also did a bunch of physics changes and other things.
There’s been a load of undocumented changes being found and collected into a single list. This article will be updated when there’s an official post by the community with all their findings.
Edit: See Black60Dragon’s Super Mario Maker 2 Version 1.1.0 Changes for a list with the findings so far.