YouTube doesn't exactly use M3, it has some similarities, but it is pretty much its own thing. The bottom area on YouTube is also not exactly the same as the Navigation Bar from M3, the Create Button is very clearly not the same as the rest. In fact, the entire bottom area looks sort of similar to the Bottom App Bar from Material Design 2

About YouTube Music and Google Podcasts. Yeah, they have an "Explore" option, but they work vastly differently from Sync, and it isn't even a matter of being a page vs bottom sheet. On Podcasts it works more like seeing the "Everything" feed than the explore sheet on Sync.

I think Sync would benefit from removing the "Explore" option, and changing "Posts" to "Everything", and adding new targets from "Local" and "Subscribed" if they want to continue using the Navigation Bar.

OR, they could swap it for a Bottom App Bar, and remove the "Posts" button, and treat the Inbox as being a subscreen rather than a main destination