While PSP seems like a reasonable protocol on its own, it is such a prime example of the left hand not knowing what the right is doing.

QUIC (over UDP) also requires encryption at its protocol layer in addition to encoding a encryption context identifier that is comparable, but non-compatible with the PSP header. So, a implementation that properly conforms to both standards would double encrypt the same data and send redundant headers/identifiers with no added security.

They could relatively easily restructure QUIC and PSP to be fully compatible, letting PSP do connection identification and encryption and then layering QUIC framing on top. But no. What a mess.