Microservices remains mostly an organisational pattern to scale development teams not necessarily the system performance. Microservices add a lot of complexity and overhead.
It's almost always relatively normal sized services split by functional area e.g. Auth, Cache etc.
This is the "Enterprise Technology Adaptation Strategy".
I don't think you mean service mesh here, or at least not Istio/Linkerd style service mesh
Serverless is RESTful, lower-level, and coupled to the cloud-provider's menu of containers, key/value store, authentication, &c.
"Synonymous" seems a stretch.
If it was literally just SOA, I wouldn't have issues with it as you can reasonable have conversations about where divisions should be placed. Maybe you are surrounded with more reasonable advocates, but that is not the norm in my experience.
When you have orgs assigning a team to build and maintain 20+ services... It's gone into full self destruct mode.