Facebook Company (Meta) has recently changed the Facebook page from the Old (Classic) to the New (New experience).
Because this new or New page experience has many differences from the Old or Classic one.
This update mainly affects the backend, and it will only be visible to the admins of the page and other people who manage the page. It doesn’t have any major impact on the users who follow your page.
In the new Page experience, the major change is that pages now look and feel like Facebook profiles. For instance, you can follow other pages and even other profiles. You have to switch to a page before you can manage it. Similarly, the notifications and messages show up at the top of the page.
So the other difference of classic page and new experience page is that in New Page experience pages get a dedicated feed that is separate from your personal feed and each page that you manage has its own separate feed. This feed wasn’t available in the classic page.
The other difference is the ability to manage profiles and pages separately. Before, all you had to do was open the page from your account and you could manage it. But now, you will need to switch to the page if you want to manage it. Simply opening the page will not give you admin or any other rights to access the page.
Source:techwiser.