when do ya think its time to look into a service mesh tho

ive been seeing a lot about service meshes like istio and linkerd lately, and they seem to offer a lot of features for managing microservices communication, security, and observability. but they also sound complex to set up and manage. at what point in a microservices journey does the complexity of a service mesh start to outweigh the benefits? are there specific indicators or pain points that signal its time to explore one