Using the https://plugin.tebex.io/user/ or https://plugin.tebex.io/payment/ api, you should be able to see the user’s spend or the purchase price in the base currency (for me GBP) as well as the checkout currency like it does in the payment webhooks.
I have a patron system where people’s spend on the store advances them, but now due to this, I have no way to get someone’s spend all in GBP