Neither showed up in notifications. It seems as if either someone has solved the problem or it has solved itself. Thanks for your help.

Thanks. I have unmuted you.

BTW in order to give the examples Mike asked for I reverted muting notifications from him, but the Wikidata notices did not come back. I then ticked 'Connection to Wikidata' and the notices reappeared. They disappeared when I unticked. Maybe this means that unticking 'Connection to Wikidata' is working now?

They are all Commons categories so far I remember. Examples are Category:Sole Common Pond, Category:Westfield Farm Chalk Bank, Category:Easton Farm Meadow, Category:Boxford Water Meadows.

The notifications are on Commons, Your notices. I get a notification that a category has been linked to Wikidata. Unticking'Connection with Wikidata' in Preferences, Notifications, appears to be the correct option to stop receiving the notices, but it does not work.