This is core to the FX (foreign exchange) business model. You have two places you can get paid: fixed transaction fees and the “spread” on the underlying exchange rate.

Most companies offering FX services will charge both.

Most consumers are not sophisticated enough to do the calculation to blend the fee into the quoted rate to get the true rate. Institutions will be.

The risk of a “no fee” pricing scheme (or why there are fees in the first place) is to avoid getting wiped out by lots of small transactions, where your per-transaction overhead dominates. OP clearly has automated enough that they are not worried about this. And given the amount of manual work still involved in FX (do not get me started on some of the process hell I saw running international payments globally over an “api” payment provider), there is also a lot of room to reduce total cost through automation.

But in summary, everyone is making money from the FX rate spread, and you are always getting charged more than the provider is paying for the currency. The question is just whether fee or spread dominates.