Assuming you are genuinely talking about your Apple Cash account it is treated by the financial networks as a Debit Card just like any bank debit card. It is managed by Green Dot Bank. So like any debit or credit card the merchant of course has your account information if you entered it during the purchase process. There’s nothing you can do about it. Knowing who has access to your debit or credit card is totally your responsibility.
As for Temu, it is a Chinese retailer that offers extremely cheap prices on all sorts of products. That in itself is a red flag for me. In my research they have many more complaints than complements.