What are the main impacts and issues when using Linkerd but all meshed services are using the same "default" ServiceAccount?

[Aracki]

I cannot understand this from the documentation.

Apart from the security concerns and wrong names for client_id in metrics, would Linkerd work seamlessly if all meshed pods are utilizing the same "default" ServiceAccount? Would it be there some issues regarding rotating secrets for mTLS?

[alpeb]

Things should work fine if you use the same SA all over the place, including mTLS. But it's good practice to have different SAs per workload; identity in linkerd is tied to SAs, so in order to apply some policy to a workload you need to refer to its SA, so it needs to be differentiated.