I am on the go so I can’t type much, but basically lack of control and insight into your service—why it’s firing or not, what is backing things up, unexpected errors can fail near silently, there’s a lot of tooling we take for granted on servers we control that you start to miss on lambda. Logging is a lot more work. Scaling is completely invisible and outside of your control. Weird OS or runtime bugs can surprise you. I don’t have a bullet list with documentation of each downside, but from experience running at a large-ish scale, it can be a lot more frustrating than you expect and the benefits in cost are not necessarily there. But again it depends on the workload and the use case. I’m not interested in making blanket statements about serverless tech. It has a promising future but the tools are just not there yet, at least not with Lambda. I don’t have experience with the competing services.