I agree that DPoP - especially the nonce - is quite complex, but I don't think it's as bad as you make out.
Proof tokens can only be used for a narrow window of time (seconds to minutes), so you just need a cache of recently seen token identifiers (jtis) to do replay detection. And proof tokens are bound to an endpoint with the htm and htu claims. They can't be used across services, so I don't see a need for that replay cache to be shared across all services.
Proof tokens can only be used for a narrow window of time (seconds to minutes), so you just need a cache of recently seen token identifiers (jtis) to do replay detection. And proof tokens are bound to an endpoint with the htm and htu claims. They can't be used across services, so I don't see a need for that replay cache to be shared across all services.