Persistent Issue with iCloud Contacts Reappearing After Deletion

I've been experiencing a recurring issue with my iCloud contacts. Despite deleting them from the iCloud website, they continually reappear. I've taken several steps to troubleshoot, including:

1. Ensuring contact syncing is turned off on both my iPhone and Mac.
2. Signing out of iCloud on all my devices.
3. Checking for other devices connected to my iCloud account.
4. Investigating potential third-party apps or services that may have access to iCloud contacts.