Thank you for your reply.
I thought same things. it was a It may be the behavior of a system that temporarily holds parameters?
so I saved the modified material data and restarted the editor, but the references still remain.
If you copy the same material to another location and create an instance from it, the reference will be removed, so
Obviously the original material refers to some invisible data.
I’m wondering if there is a way to get rid of this apparently unnecessary reference and clean it up, but is there such a way?
(I think there is a smart way, not a brute force method like the above new copy and forced deletion of the original material …)