I see. To clarify, may we know how you’re adding the custom Author meta image specifically?
If you added a post meta field, one way to retrieve it is through a PHP like this:
add_filter( 'generate_post_author_output', 'tu_custom_author_image' );
function tu_custom_author_image( $output ) {
$my_image = get_the_author_meta('img-author', get_the_author_meta( 'ID' ));
if ( $my_image ) {
return '<img src="'. $my_image . '" class="avatar"/>' . $output;
} else {
return $output;
}
}
Kindly replace img-author with the field name of your Author meta. Then, make sure the return type of the field is URL.
Adding PHP reference: https://docs.generatepress.com/article/adding-php/#code-snippets
Hope this helps!