This just isn't true. Airbnb is actively using React Native a lot and has not "stopped using it seriously". I'm not sure where you got this impression. Some people responding to this are mentioning the transition of the potential native-navigation library to react-community. This is a library that we never actually used in production, though the plan was to move off of our internal library to this one shortly after open sourcing it. Priorities shifted internally (to other, more pressing react-native related things that aren't OSS), and we have not yet been able to do that. Since the community really wanted to work on the library despite us not actively maintaining it, transitioning it to react-community seemed like a better thing to do than further fragment the community by having people fork it. I'm still hopeful that we will be able to migrate to it in the future.
Source: I am the tech lead of React Native infrastructure at Airbnb and the primary author of native-navigation.