currently, as confirmed by Microsoft support, when user logs into office 365 on the customer side, they after choosing the dynamics 365 business central icon, are then presented with two main options, production and sandbox. However, the sandbox one is based on the default created sandbox, regardless of how many other sandboxes are created. Additionally user cannot change the selection of that sandbox, or know which sandbox they are in. Thus, it would be nice to have more tiles appear for more sandboxes, and have each sandbox appropriately named with the actual sandbox name.
Under Review
Ideas Administrator

Thanks for the feedback! This is a great suggestion. With an upcoming release we will be introducing the ability to have multiple production environments within an AAD tenant, which, with multiple sandboxes, increase the need for the ability to easily recognize in which environment you are working and effectively switch to another environment. We are looking into ways to accomplish this, which may also include switching environments from the tiles on the "waffle". We'll continue tracking this suggestion for votes, as well, in prioritizing improving this experience in a future release of Business Central.

Best regards,
The Business Central Team