Don't redirect add to cart form on WooCommerce archive pages. https://iconicwp.com/blog/show-variations-shop-page-woocommerce/#comment-356

add-to-cart-redirect.php

<?php

/**
 * Don't redirect on archive pages.
 * 
 * @param string $redirect
 *
 * @return string
 */
function iconic_add_to_cart_form_action( $redirect ) {
	if ( ! is_archive() ) {
		return $redirect;
	}
	
	return '';
}

add_filter( 'woocommerce_add_to_cart_form_action', 'iconic_add_to_cart_form_action' );