PSA: Purse tried to overcharge me, and it's fishy

I submitted an order with a pre-tax total of $26.40. The tax was a normal looking amount, $1.59.

Then I got an email about a price change. (This happens relatively often, supposedly because it's hard for Purse to estimate exactly how much things like tax and shipping will be.) The $1.59 changed to $7.80. That would mean that the sales tax was almost 30%, which would be crazy high.

I contacted support, and the response I got was worrying. They said "This is the tax price of your order in Amazon." and sent this picture:

https://imgur.com/a/TWmQPJU

But as you can see, the order they showed there included a $114 Apple TV which was NOT in my order.

When I pointed this out, the support representative said "the system added an item by mistake to the calculation, I will report the issue to the dev team" and they adjusted the tax amount for my order to $0.96.

So that's all fine and good, but how many Purse.io shoppers have been paying extra tax because of this kind of "mistake"? The amount added to my order was more than I was saving by using Purse in the first place!

And why on earth would there be an extra item in the order on their end? I can only hope that this actually is just a mistake, and that Purse.io hasn't been scamming their users by getting them to pay the sales tax on extra items.