I don’t want the visual clutter.

greasemonkey / custom css

If the main purpose of topic tags is to allow filtering and aggregation, the tags don't need to be that visible/prominent in the first place.

I'm not saying this is the answer either, because I don't know if it's a great fit for HN, but managing and verifying such tags would fit well into somethingkme the ol' the moderation and Meta-moderation systems from Slashdot.

(Using LLMs to generate initial topic tags once per article instead of having independent implementations burn up compute over it dynamically also seems like a way more reasonable way to use them toward this end.)