Google knows when we click on ads. But now, Google also knows what we buy in brick-and-mortar shops, due to a previously unreported deal it cut with Mastercard to get our transaction histories.

Google has already bragged about: it claims to have access to about 70% of US credit and debit cards information

https://nakedsecurity.sophos.com/2018/09/03/google-quietly-bought-mastercard-credit-and-debit-card-records/