The OIDC JWTRequest concept has been generalized in its own dedicated spec RFC 9101 The OAuth 2.0 Authorization Framework: JWT-Secured Authorization Request (JAR).

Basically, it consists in making clients pass authentication request details in a JWT instead of a query string. The JWT is the passed as a request parameter, or hosted on a client endpoint which url is passed as a request_uri parameter.

It would be nice for Authlib to implement this spec.