From Shruti Kapoor on PayPal’s technology blog:

We started our GraphQL adoption journey by building our checkout experience. We saw tremendous benefits in adopting GraphQL when our checkout app built with GraphQL became our guiding light.We built more apps, provided infrastructure support, launched a public GraphQL API, and provided trainings and learning materials across the company. We also set up a standards body, provided a GraphQL tools fanny pack, and built sample apps to help teams get started.

Today, GraphQL is being used by several production apps across PayPal. It is now a default pattern to use GraphQL for building new UI apps. Many existing apps are in the process of migrating to GraphQL.