It just doesn't. Created a staging copy of the site, disabled all unneeded plugins, activated Twenty Twenty-three, copied sample code from the settings into the render file.
I have discovered the problem is that rwmb_meta( 'field_name', [ 'object_type' => 'block' ] ); does not work for any block field, and mb_get_block_field() and mb_the_block_field() must be used.