function panel_strip_comic_image( $content ) {
	if ( class_exists( 'Jetpack_Comic' ) && ( Jetpack_Comic::POST_TYPE === get_post_type() ) && has_post_thumbnail() ) {
		$image_url = wp_get_attachment_image_src( get_post_thumbnail_id(), 'full' )[0];
		$image_url = str_replace( array( 'http://', 'https://' ), 'https?://', $image_url );
		$regex     = sprintf( '#<a href="%1$s"><img[^>]*? src="%1$s[^"]*" [^>]*?/></a>#', $image_url );
		$content   = preg_replace( $regex, '', $content );
	}

	return $content;
}
add_filter( 'the_content', 'panel_strip_comic_image' );