What do Tink (and other open banking providers) do with their transaction data?

They must process millions of transaction data daily. Obviously with GDPR they're not allowed to sell it if it contains any personally identifiable information.

But it's not so hard to anonymize transactions, especially for countries like the UK where everyone goes to the same shops (Tesco, John Lewis, etc). This data would be super valuable, and with statistics the sample size needed isn't as big as you think. It could be a finger on the pulse of the economy.

So I was wondering if anyone knows anything about this!?