get_post_format()

get_post_format( int|WP_Post|null $post = null ): string|false

function get_post_format( $post = null ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return false;
	}

	if ( ! post_type_supports( $post->post_type, 'post-formats' ) ) {
		return false;
	}

	$_format = get_the_terms( $post->ID, 'post_format' );

	if ( empty( $_format ) ) {
		return false;
	}

	$format = reset( $_format );

	return str_replace( 'post-format-', '', $format->slug );
}