Limit WooCommerce products in cart only from one custom taxonomy

add_filter( 'woocommerce_add_to_cart_validation', 'only_one_supplier_by_order', 10, 2 );
function only_one_supplier_by_order( $passed, $product_id ) {
    if ( WC()->cart->is_empty() )  
        return $passed;
    
    $taxonomy = 'supplier';
    $term_ids = wp_get_post_terms( $product_id, $taxonomy, ['fields' => 'ids']);

    // Loop through cart items
    foreach ( WC()->cart->get_cart() as $cart_item ) {
        if( ! has_term( $term_ids, $taxonomy, $cart_item['product_id'] ) ) {
            // Displaying a custom notice
            wc_add_notice( __('This product is with a different supplier. Please only order from 1 supplier at a time.'), 'error' );
            return false; // Avoid add to cart
        }
    }
    return $passed;
}

// To be sure (avoiding checkout)
add_action( 'woocommerce_check_cart_items', 'only_one_supplier_by_order_check' );
function only_one_supplier_by_order_check() {
    $taxonomy   = 'supplier';
    $term_names = []; // Initializing

    // Loop through cart items
    foreach ( WC()->cart->get_cart() as $cart_item ) {
        $terms = wp_get_post_terms( $cart_item['product_id'], $taxonomy );
        if( ! empty($terms) ) {
            $term  = reset($terms);
            
            $term_names[$term->term_id] = $term->name;  
        }
    }

    // Allow only one supplier in cart (avoid checkout for more than one
    if( count( $term_names ) > 1 ) {

        // Displaying a custom notice
        wc_add_notice( __('Only items from one supplier at the time are allowed in cart'), 'error' );
    }
}