Ask HN: When does serverless become more expensive than microservices?

If it makes sense to deploy an application both as serverless as well as microservices, when will a serverless architecture start being more expensive economically, or in general having tradeoffs in comparison to microservices. Again, the question relates to cases in which both architectures would make sense for a particular application.

Other than maybe vendor lock-in, and cold starts, what other drawbacks does serverless have in comparison to microservices?