React Native is excellent for web teams that are creating a new mobile app. If your team has more experience with React than native iOS/Android, then it's a no-brainer.
However, in my experience you get diminishing returns once your app has passed v1 and your customers expect more after the new-ness wears off. You find yourself spending more and more engineering effort to make your RN app to feel as good as existing mature native-first apps, which is especially frustrating as you are solving problems that native-first app developers never had to solve in the first place. They got the solutions for free with the native sdks.
This plateau of developer effectiveness is hard to get away from as your app becomes so coupled to RN and your team invests so much into RN tooling and skills that it feels like a sunk cost.
I do not envy the Discord apps team.