Change the message seen by a customer after product variation is added to the Shopping Cart.

Drupal Commerce 2.x: Customize Add toCart message

<?php

/**
 * Implements hook_commerce_add_to_cart_message_alter().
 *
 * Apply this patch: https://www.drupal.org/node/2905624#comment-12242300
 * Place this code into YOUR_MODULE.module file replacing YOUR_MODULE placeholder
 * with your modules' name.
 */
function YOUR_MODULE_commerce_add_to_cart_message_alter(&$message, &$order, &$order_item) {
  // Alter $message or $order or $order_item data for your needs.
  // For example, do not show Add to cart message at all:
  $message = [];
}