Disable Specific Shipping Method based on Category

functions.php

<?php
// =========================================================================
// UNSET SPECIFIC SHIPPING METHOD BASED ON CATEGORY IN THE CART
// =========================================================================
function unset_shipping_based_on_category( $rates) {
    $gift_in_cart = false;
    
    // Gift
    foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {
        if ( has_term( 'nem-virag', 'product_cat', $cart_item['product_id'] ) ) {
            $gift_in_cart = true;
            break;
        }
    }
    if($gift_in_cart) {
        unset( $rates['flat_rate:20'] );
    }
    return $rates;
} 
add_filter( 'woocommerce_package_rates', 'unset_shipping_based_on_category');