Multiple Scrum Teams working on the same product or system all select work from the...

According to the Scrum Guide1, when multiple Scrum Teams are working together on one product, they must coordinate their work with each other. One way to do this is through Nexus, a framework for scaling Scrum. Nexus helps to reduce cross-team dependencies and integration issues by making them more transparent. Multiple Scrum Teams working on one product use one Product Backlog.

References: Scrum Guide, Nexus Guide