After I dropped an index on a large table, all of a sudden my disk space was almost filled, even though I dropped it. Now, I’m looking at my mysql directory and there are a whole bunch of large IBD files labled as fts_*_being_deleted_cache.ibd. I’m on MySQL 8.0. I have rebooted the server, but these files are still there. Can I delete them? What are they? They clearly are not being deleted.

I also have a huge slew of fts_*.ibd files that I have no idea what they are and I do not have any full-text indices. Can I tell what these are and whether they can be deleted?