Is there a way to filter article:author?

Maybe this is a race condition issue, because your filter might be called too early. Maybe add a lower priority, to be sure to be called later as the default filters:

add_filter( 'opengraph_metadata', 'my_opengraph_metadata', 1, 20 );

Thank you, that was it. This worked:

function my_opengraph_metadata( $metadata ) {
    unset( $metadata['article:author'] );
    return $metadata;
}
add_filter( 'opengraph_metadata', 'my_opengraph_metadata', 20, 1 );

Would be a nice one to add to the docs.

Ooops, I twisted the params 🙂

..but I am glad it works!