The "crit" (critical) Header Parameter indicates that extensions to this
specification and/or [JWA][] are being used that MUST be understood and
processed. Its value is an array listing the Header Parameter names present in
the JOSE Header that use those extensions. If any of the listed extension
Header Parameters are not understood and supported by the recipient, then the
JWS is invalid. Producers MUST NOT include Header Parameter names defined by
this specification or [JWA][] for use with JWS, duplicate names, or names that
do not occur as Header Parameter names within the JOSE Header in the "crit"
list. Producers MUST NOT use the empty list "[]" as the "crit" value.
Recipients MAY consider the JWS to be invalid if the critical list contains any
Header Parameter names defined by this specification or [JWA][] for use with
JWS or if any other constraints on its use are violated. When used, this Header
Parameter MUST be integrity protected; therefore, it MUST occur only within the
JWS Protected Header. Use of this Header Parameter is OPTIONAL. This Header
Parameter MUST be understood and processed by implementations.

[JWA]: https://datatracker.ietf.org/doc/html/rfc7518