Next.js and Firebase Expert to Audit and Fix Authentication Flow

We are looking for a senior developer with proven experience in Next.js (App Router) and FirebaseUI to audit and resolve a persistent issue in the authentication flow of our real estate investment platform. The application is built with a modern stack (TypeScript, TailwindCSS, shadcn/ui, Firebase) and already has an advanced codebase. The work consists of surgical debugging and refactoring, not building from scratch.