Incorrect hostCurrencyFxRate and amountInHostCurrency with some PayPal expenses

[znarf]

When paying an Expense with PayPal, we're reading the hostCurrencyFxRate from PayPal response but it's sometimes inaccurate to do so. It's especially visible for Transactions that have currency = hostCurrency.

https://github.com/opencollective/opencollective-api/blob/master/server/lib/transactions.js#L117

SELECT * FROM "Transactions"
WHERE "deletedAt" IS NULL
AND "ExpenseId" IS NOT NULL
AND "currency" = "hostCurrency"
AND "hostCurrencyFxRate" != 1;

We should review this and fix past entries in the ledger.

[kewitz]

@znarf
This bug happened only once in 2021 and twice in 2020.
It affects only Adaptive Payments, which PayPal deprecated and continues to provide support to existing integrations only.

I suggest deprecating adaptive payments on our side as well and enabling PayPal Payouts for everyone:
#4210

[znarf]

Ok, I think it might be slightly misleading to look at the data as it is today, because I fixed many impacted transactions.

But if it doesn't happen anymore, that's good to know and we don't have to look at a fix I guess.