The I-D looks good.

However, I'm slightly confused about the terminology used in section 3.1
3.1.  Header Field Compression

"If the connection between the TTRP and origin is capable of field
   compression (e.g., HPACK [HPACK] or QPACK [QPACK]), and the TTRP
   multiplexes more than one client's requests into that connection, the
   size and variation of Client-Cert and Client-Cert-Chain field values
   can reduce compression efficiency significantly."

Do the authors mean origin server ?