[7.4-8] MUST: Since the TE header field only applies to the immediate connection, a sender of TE MUST also send a ...

[saviorand]

RFC 9112 Requirement

Section: 7.4-8 Keyword: MUST

Since the TE header field only applies to the immediate connection, a sender of TE MUST also send a "TE" connection option within the Connection header field (Section 7.6.1 of [HTTP]) in order to prevent the TE header field from being forwarded by intermediaries that do not support its semantics.¶

Reference: https://www.rfc-editor.org/rfc/rfc9112.html#section-7.4-8