Do you mean before or after the swap has been committed? There is already a banner for before, and there’s a feature request to notify beforehand:
https://forum.inaturalist.org/t/notify-users-of-drafted-taxon-changes/38765
Users also get notified of taxon changes on their dashboards. Are you requesting that a note be added that large taxon changes take a while to finish?
This particular instance is unusual because it was reversed and that makes things wonky.