Create custom Gutenberg category. #wordpress #gutenberg

custom-gutenberg-category.php

function custom_gutenberg_category( $categories, $post ) {
	return array_merge(
		$categories,
		array(
			array(
				'slug' => 'custom',
				'title' => __( 'Custom', 'custom' ),
			),
		)
	);
}
add_filter( 'block_categories', 'custom_gutenberg_category', 10, 2);