when does API Gateway become a bottleneck

Hey everyone, I've been thinking about API Gateways lately. They're really useful for routing, authentication, and rate limiting, but I'm starting to wonder if they could become a bottleneck. When request volume or complexity gets high enough, when should we worry about our API Gateway being the weak link? Are there specific metrics or design patterns that show us it's time to scale it up or maybe even rethink its job? I'd love to hear what you all have experienced and think!