Possible Solution to Tag Spam
My suggestion is a bar below the project description. When making a project, the user could click the dropdown menu on the bar and select one of the categories on the explore page.

This would work a bit like the project tags system in 2.0, but you would only be able to select categories on the Explore page, and instead of a limit of 3 tags, you could only have 1.

This could stop tag spamming, because who would tag “art” or “music” on their game instead of “game”?

Mockup (not very good): https://scratch.mit.edu/projects/990853285/

(Sorry if this is a duplicate or rejected, I checked the Suggestions Directory and the Official List of Rejected Suggestions.)