Reference Field cannot be deleted, even when it's not linked anywhere

I’m trying to delete a category field (reference field) on my blog collection. These collections don’t have links or bind anywhere through the project. However, it keeps saying that it has.

So, here’s my collection

When I try to delete the field I got this:

When I go to check the connections, it doesn’t list anything and says something strange:

If I go to check the connection on the Category Collection I get this:

And of course, if try to delete de Category Collection it says that I’m linked to the field mentioned above:

So there’s a loop here that doesn’t allow me to delete this. Do you guys have any clues?