Change the suffix price when price is entered excluding tax and displayed in including tax

Modify price suffix behavior for tax-inclusive display with tax-excluded suffix.

add_filter('woo_discount_rules_discounted_suffix_price', function ($price_suffix, $product){
    if ( $product->is_taxable()  ) {
        if(class_exists('WC_Tax')){
            $tax_rates      = WC_Tax::get_rates( $product->get_tax_class() );
            $base_tax_rates = WC_Tax::get_base_tax_rates( $product->get_tax_class( 'unfiltered' ) );
            $remove_taxes   = apply_filters( 'woocommerce_adjust_non_base_location_prices', true ) ? WC_Tax::calc_tax( $price_suffix, $base_tax_rates, true ) : WC_Tax::calc_tax( $price_suffix, $tax_rates, true );
            $price_suffix   = $price_suffix - array_sum( $remove_taxes ); // Unrounded since we're dealing with tax inclusive prices. Matches logic in cart-totals class. @see adjust_non_base_location_price.
        }
    }

    return $price_suffix;

}, 10, 2);