While watching my Apple TV this evening I received an email “You’re managing a new Apple TV profile”. This said a new profile for “John” had been created. Sure enough when I looked at the profiles on the Apple TV there was a new one for “John”. Needless to say I went straight to Settings and deleted it (requiring confirmation on my iPhone).
There was no way I did anything that could have accidentally created this profile or accepted a request to create it. I hope there is not a vulnerability in tvOS that caused this!
If it’s an Apple ID, then something added that ID to your Apple TV. I’m not sure how that’s possible without physical access to your device. Especially since you were watching TV at the time.
If it’s a “Managed” profile, that’s part of your Apple ID/account. These can (I think) be created by anyone with access to your account, even if they’re at a remote location.
Should I assume that nobody else (perhaps a child of yours) has access to your Apple ID and password?
You may want to change your password right away and double-check to make sure nothing else in your account was changed (e.g., new mailboxes, purchases, subscriptions, etc.)
If you haven’t already set up 2FA or a Passkey, I recommend you do that too.