rename member group of group-connected site

I would like to apply a PnP template to a group connected site, but I receive an error message that the group name contains not allowed characters. True, it has / in its name. I renamed the group in Teams, this looks ok,but in SharePoint I still see the old name, that is like Customer A/B members. When I try to edit in SPO, I can see that the object behind this group is like c:0o.c|federateddirectoryclaimprovider|76cba1c7-42f0-4571-9245- and I cannot do anything with it. Where does this object live and how can I rename it?