We do a react app on the frontend and actix+diesel REST API, with Keycloak JWTs for user management. The actix+diesel REST API is much more solid and less troubling than another python flask API we have.

I still think frontend/backend split is useful for the types of applications my team works on. Stateful, interactive UI clients written in React, without round trips for full page loads is going to be our choice until a Rust WASM frontend client system reaches maturity.