How to permanently delete super cookies in ios15.1

Since installing ios15.1, Safari shows several zero cookies with zero data, which reappear after individually deleting, or via removing all website data (Safari/Advanced/Website data/Remove all website data).

I have repeated that process with JavaScript disabled, and also with all Safari/Advanced/Experimental Features disables. Also tried signing out and back of iCloud.

Any suggestions, short of having to hard reset my iPad Pro M1?