The Apple TV app accessed content based on the region of the Apple ID account, which is based on your billing address. If somehow there is a region mismatch between what the app ‘thinks’ and what the account ‘thinks’, then you may get locked out for that content.
To solve the mismatch, sign out of the Apple ID account for the iTunes Store & App Store, then sign in again. That should get them aligned again.
You are not allowed to access other region stores (other than browsing). Your access to the iTunes Store is intended for “your home country” only, per the Apple/iTunes terms and conditions.
If someone shared a link with you for out-of-region content, then that may have prompted your phone to see if it is available in another region Store, even though you can’t get it there. That may have caused a mismatch for the iTunes Store and the Apple ID account.