You can now add tags when you create a post. Available tags show up show up in a dropdown, or you can create a new one. The community can then filter and sort by those tags.
I suspect that the tags are visible system-wide, so perhaps avoid stuff that’ll create havoc.
I actively dislike it. But that’s how Discourse works. You can circumvent it by adding a trailing space or deleting the final period. But if you just add bolding or something it will still delete the post. Without warning you.
Honestly, if it warned you in the preview, I wouldn’t hate it as much.