The Scrum guide encourages that if multiple teams are working on the same product then they should all use a single product backlog and have a single product owner.
How realistic is that? Consider this example:
In a ride hailing app (similar to Uber) they have more than 6 teams. Each team handles a certain functionality of the app.
1) User registration and profile management.
2) Maps and user locations.
3) Pre ride.
4) In-ride management.
5) Post ride management.
6) Payments.
7) ...more teams.