tax_query in get_posts() not working?

tax_query takes an array of tax query arguments arrays (it takes an array of arrays) but you are using only single array. The correct code is as following.

$uposts = get_posts(
    array(
        'post_type' => 'product',
        'numberposts' => -1,
        'tax_query' => array(
            array(
                'taxonomy' => $cat->taxonomy,
                'field' => 'slug',
                'terms' => array($cat->slug),
                'operator' => 'IN',
            )
         )
    )
);

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