wiaver of subrogation for professional liability a thing?

Forgive my ignorance, I’m just hoping for some generalized feedback:

I’m a licensed land surveyor in the US. A client is asking we provide a waiver of subrogation for our professional liability policy. My provider said they don’t do that for professional liability policies.

This surprised me as it’s a large nationwide provider (though I assume they started in a Connecticut city 😉

Is the uncommon part the client asking for this or the provider not offering it?

(This is pacific to the Professional Liability. They were quick to provide the waiver for our general liability)