Went to switch from our main tenant to a test tenant (Azure Active Directory, Overview, switch) and there was a third tenant from another company listed.
I'm the admin and I've not made any associated changes to our tenant's relationship. They are one of our clients but there's no formal connection in AD, Sharepoint, Teams, Exchange (e.g. Organization sharing) etc
Anyone know why it might appear or where I might be able to find what's causing it?