Sometimes useful features show up in a Microsoft 365 app long after they should have been there. This is the case of SharePoint Online’s document library dropdown menu, which is very helpful in navigating sites with multiple libraries. Unfortunately, not too many sites have multiple libraries because most are Teams-enabled and have a single library. Teams is another app where features show up after they should. The listing of the teams a user belongs to in the Teams admin center is a good example.
https://office365itpros.com/2022/04/01/sharepoint-document-library-dropdown-menu/
