category-shop-base.php

<?php

add_filter( 'rewrite_rules_array', function( $rules ) {
    $new_rules = array(
        'shop/([^/]*?)/page/([0-9]{1,})/?$' => 'index.php?product_cat=$matches[1]&paged=$matches[2]',
        'shop/([^/]*?)/?$' => 'index.php?product_cat=$matches[1]',
    );
    return $new_rules + $rules;
} );

Add the above rewrite rules to either the child theme's functions.php or better still, use a site functions plugin.