@WhiteNoise I came here to report this exact same thing. #s inside URLs and internal links is being recognised as a tag.
(v0.8.8, macOS Catalina)
Since this post is already in the graveyard, shall I create a new bug report?
UPDATE:
Well, it’s partially sorted out. I did indeed have a #s inside one of the notes, and so it made sense that the tag appeared in the tags panel.
The confusing part is all those incorrect matches in the search that’s invoked by clicking the tag. They shouldn’t be there, should they? The search queries generated by tags should show tags only.