How to update DHT after garbage collection?

At the moment no, we just wait until the provider records expire (24 hours, I think?). In general, deleting records from DHTs is difficult to impossible; all you can really do is replace it with a record saying “this other record is invalid”. Also, publishing (and deleting) provider records is time consuming so we’d like to avoid doing so when possible.

It may make sense to have some way to delete provider records for popular content (on a best-effort, when necessary basis). However, figuring out how to do that correctly is non-trivial so it’s not really a priority (this isn’t really a burning issue at the moment so it’s unclear if deleting provider records will save much bandwidth).