Why there is an unknown suspicious user in our amazon brand registry?

We recently discovered an unknown suspicious in our Amazon Brand Registry account. No one in our company has set this up, yet this user can access one of our brands.

We opened a case and received a response stating: "Be aware that adding or removing users from a particular brand is something internal to the brand. Only the administrator of the brand can add or remove users. We don’t have any tools that can perform such actions." However, we are sure that no one from our company set up this user.

It’s quite strange. Has anyone else encountered a similar issue? Does anyone know why there might be an unexpected user added?