[nostrebored]

Warming functions in the previous VPC architecture was always a questionable practice. You had no guarantee that your environments would be warm across all subnets or which subnets would handle incoming requests. Beyond that, what happens to requests which you receive when the function is being warmed? You still incur cold starts.

There has never been a guarantee of environment reuse. Any architecture which isn't capable of incurring cold starts is not a good fit for serverless.