Fixed it by changing to
add_action( 'wp_enqueue_scripts', 'remove_hooks' );
function remove_hooks(){
global $wp_query;
$postid = $wp_query->post->ID;
$format = get_post_format( $postid );
if ($format == 'gallery') {
remove_action('wp_head', 'amp_frontend_add_canonical',10);
}
}