Previously, content from other streaming services was mixed in and it wasn’t obvious that you can’t watch it without an additional subscription.
Amazon Prime Video is a streaming service, but also a hub that allows you to use other streaming services (e.g. Max). This is cool and all, but it can get a little confusing about what you can and can’t watch at no additional cost. Amazon is currently rolling out a redesigned UI that fixes that and brings other improvements too.
In the new UI, there are several tabs on the top row. By default, there is a Prime tab, which only shows movies and TV shows that are available with your Prime subscription. Next to that is the Subscriptions tab where you can add partner services.
The homescreen of Prime Video will still show additional content – that is titles that you have to rent/buy as well as content from the mentioned partner services (even ones that you are not subscribed to).