Mobile and online payment services such as Alipay and WeChat Pay are depriving China’s banks of processing payments but, more importantly, cutting them off from users’ transaction data, reported Financial Times.

Eric Jing, president of Ant Financial, said payments through its Alipay unit bypass China Unionpay’s settlement network, as well as issuing and acquiring banks. All these parties are losing income from merchant fees.

Chinese research firm Kapronasia calculated that the move to smartphone payments from credit/debit cards had removed $20 billion in fees from Chinese banks in 2015, a massive chunk of income.

However, there could be a bigger problem heading the way of the country’s banks thanks to mobile payments, because the providers of such services sit between traditional financial institutions and end users.

Users of Alipay and WeChat Pay fund payments by linking the wallet apps to their bank accounts. When a payment is made via smartphone the bank does not receive information, such as identity of merchant and location, but only notification that the transaction was handled by Alipay or WeChat, for instance.

Being starved of such data makes it harder for traditional banks to understand the consumption habits of their users, and plan new services that might attract them.