After using the "Delete your listens" option, some of the listens reappear after a few minutes, as if they were never deleted. Apparently, this is only happening to listens made in Spotify.

The Delete your listens section of the profile page should mention that if you are still connected to import Spotify listens the last 50 Spotify tracks will be reimported automatically.

That bit of text should have a link to the connect-spotify page to allow users to easily find the page to disconnect.