Shein not refunding tax for partial returns/cancellations

When you make a partial refund on an order, you don't get that portion of your taxes refunded. I contacted customer service about this because I believe it's a legal consumer right to have both sale items and tax proportionate to the items be refunded, but they only refund cost of the sale items.

They first replied with:

Regarding this, the amount that is applied for refund is the price of the items that you have paid. If the order is not fully cancelled, the taxes will not be applied for refund application since there are some items in the order. Thank you

then later replied with:

The tax for the item is included in the price of the item already regarding this - *which is not true* because we pay for tax on top of the items we paid for.

The tax isn't a lot, but it's more so about the principle for me. I just wanted to let all the baddies know in case they need to double check their refunds.