What is this and how can I delete this?
I experienced this some time ago. I forget the details, but it is related to group labels.
My memory of what caused it is not 100%, but think it occurred when I deleted all members of a group except one.
Edit:
It’s coming back to me now. If the group name is too long to fit in the space in the group bracket, the group name defaults to a number corresponding to the order in which groups were created. Until groups are renamed, they will be called Group 1, Group 2, Group 3, etc. With a group consisting of only one player the bracket will be quite short. In your example, the group would have been the third group to be created.
Thanks! Yes, it ist from an “empty group” in the setting area. I deleted it, and the sign was gone.