[9.3.2-4] SHOULD: An intermediary that receives pipelined requests SHOULD pipeline those requests when forwarding them...

[saviorand]

RFC 9112 Requirement

Section: 9.3.2-4 Keyword: SHOULD

An intermediary that receives pipelined requests SHOULD pipeline those requests when forwarding them inbound, since it can rely on the outbound user agent(s) to determine what requests can be safely pipelined. If the inbound connection fails before receiving a response, the pipelining intermediary MAY attempt to retry a sequence of requests that have yet to receive a response if the requests all have idempotent methods; otherwise, the pipelining intermediary SHOULD forward any received responses and then close the corresponding outbound connection(s) so that the outbound user agent(s) can recover accordingly.¶

Reference: https://www.rfc-editor.org/rfc/rfc9112.html#section-9.3.2-4