Moving from one back end to another requires some input from customers, which explains why there are still some customers using the legacy infrastructure. Over the coming months, Qonto plans to launch new payment features that should convince more users to switch to Qonto’s back end.

https://techcrunch.com/2020/01/20/challenger-business-bank-qonto-raises-115-million-round-led-by-tencent-and-dst-global/