When to move from Netlify/Vercel to AWS/Cloudflare for scalability?

No, we don't have such situations. Both Netlify and Vercel are very scalable. Basically, there are no limits on how big your app can be, because they both run on top of AWS or Azure and other bigger services like those. Usually if you want to switch, it's because of a specific feature -- maybe pricing, maybe you have better deal -- but it's not about limitations of the platform itself, like executions, bandwidth or stuff like that.