But I didn't click Answer, I clicked Edit

[JammyDodger]

Actually, it looks like the Post Voting plugin.

I believe there’s an existing Contribute > UX topic about this:

Change 'Answer' button back to 'Save Edit' when editing a Post Voting post

When I edit the original topic the button that would normally say “Save Edit” now says “Answer”. It has the functionality of save edit, or seems to, so as it is currently I find it misleading/unhelpful/confusing.