How can I fix Reminders not syncing correctly between my iPad and iPhone?

iPad 9th gen, iPhone 13. Both on latest iOS.

They stopped syncing, so I did the recommended fixes, ending with switching off iCloud sync, deleting tasks, so forcing a re-download from iCloud. 12 hours later, the iPhone looks right, but the iPad has stopped downloading with 60 less tasks then the iPhone has. The iPad is working fine in other respects. Do I just keep repeating this fix and hope that it works, or is there another option?

[Re-Titled by Moderator]