I see, this means that a customization has been applied to the email template, either using a filter (woocommerce_get_order_item_totals) or directly in the template (here), by changing $totals = $order->get_order_item_totals();
to $totals = $order->get_order_item_totals('excl');
.
I suspect it’s the latter, but this is something you or your site developer should check. If this is indeed the case I recommend switching this over to using the woocommerce_get_order_item_totals
filter which will then make this appear universally like that. You could also set the “Display prices during cart and checkout” setting under WooCommerce > Settings > Tax to “Excluding tax”, which will have the same effect (but of course also in the checkout and cart so I don’t know if that’s ok for your site).
Since this concerns a customization, we cannot provide further support for this. If you want full control over how the prices are displayed in the totals (regardless of woocommerce email/checkout/cart tax settings) we offer the Premium Templates extension that allows you to do this with the customizer.
Hope that helps!