I had no idea where to ask such a question and I tried to read their terms of use / privacy statements / about us page to find info about how this popular cost splitting app makes money to employ people.
They don't even accept donations. Sounds very sketchy, but apparently they don't really sell data or even offer this app to businesses. Does anyone know how they make profit?
You have made an assumption that they are making a profit. They could be in Startup phase where they are getting their product to market before finalising the monetization method in place.
The guess out of my ass is that they either plan to provide an information pipeline to financial institutions for customer modelling or be bought out by the current Dutch player called Tikkie.