How to designate Person as Pet?

In Apple Photos on iPhone, in the previous version I manually added my cat as a Person. It did not recognize it by name as an individual, but that did not bother me, I just added photos manually.

But now, happily, Apple added a Pet recognition to Photos. The tech works great. However I cannot merge my old PersonCat to the PetCat if you know what I mean. You can merge different People, but you can’t merge Pets with People.

Removing the name from the PersonCat does not work: it just becomes a nameless Person. One of my other Cats, for who I did the same earlier, does not show up as Pet at all. I fear me adding him manually as Person messed up the database. First I thought it would take some time, but we’re lots of days and phone charging further.

(Exactly same story for Sonoma MacBook)

Anyone experiencing the same and/or know what to do?