Mu-plugin code that continuously assigns (currently unassigned) product attribute terms to products, then creates yet more unassigned product attribute terms. This purposefully uses the WP API and avoids the WC API, as a way to replicate conditions that *might* lead to the problem described in https://github.com/woocommerce/woocommerce/issues/17355

scenarios-for-17355.php

<?php
/**
 * Assigns currently unassigned product attribute terms to products, to try and
 * replicate the problem in the linked issue. Also generates new unassigned terms
 * on each request, to further exacerbate things.
 *
 * We deliberately do not use the WooCommerce API, because in this case we are
 * try to circumvent WC's cache invalidation logic.
 *
 * @see https://github.com/woocommerce/woocommerce/issues/17355
 */

function get_random_product(): int {
	$count = array_sum( (array) wp_count_posts( 'product' ) );

	if ( $count < 1 ) {
		return 0;
	}

	$product = wc_get_products( [
		'limit'  => 1,
		'page'   => rand( 1, $count ),
		'return' => 'ids',
	] );

	return (int) ( empty( $product ) ? 0 : current( $product ) );
}

add_action( 'wp_loaded', function () {
	foreach ( get_taxonomies() as $registered_taxonomy ) {
		// Find product attribute taxonomies.
		if ( ! str_starts_with( $registered_taxonomy, 'pa_' ) ) {
			continue;
		}

		// Grab the attribute terms.
		$product_attribute_terms = get_terms( [
			'taxonomy'   => $registered_taxonomy,
			'hide_empty' => false,
		] );

		// Find unassigned terms, and assign them to random products.
		foreach ( $product_attribute_terms as $term ) {
			if ( $term->count ) {
				continue;
			}

			// Pick a random product and assign this term to it.
			$product = get_random_product();

			if ( ! $product ) {
				continue;
			}

			wp_set_object_terms( $product, $term->term_id, $registered_taxonomy, true );
		}

		// Last but not least, keep generating new attribute terms (to exacerbate the problem).
		$debug = wp_insert_term(
			hash( 'md5', uniqid() . rand( 0, PHP_INT_MAX ) . date( 'Y-m-d H:i:s' ) ),
			$registered_taxonomy
		);
	}
} );