WooCommerce: Discount for Logged-In Users

/**
 * Apply a 10% member discount for logged-in users.
 *
 * @param string     $price   The current price.
 * @param WC_Product $product The product object.
 * @return string
 */
add_filter( 'woocommerce_product_get_price', function( string $price, WC_Product $product ): string {
    if ( ! is_user_logged_in() || is_admin() ) {
        return $price;
    }

    // Only apply to simple products.
    if ( 'simple' !== $product->get_type() ) {
        return $price;
    }

    return (string) round( (float) $price * 0.9, 2 );
}, 10, 2 );

/**
 * Show a notice about the member discount.
 */
add_action( 'woocommerce_before_shop_loop', function(): void {
    if ( is_user_logged_in() ) {
        wc_print_notice(
            __( 'You are getting a 10% member discount on all products!', 'theme-domain' ),
            'notice'
        );
    }
} );