As you can see they're denying that this is used for customer identification, but who knows. It seems extremely suspicious to me that they'd go so far as to implement AI to identify individual faces, but then do nothing with it.
What I do know is that there is a company called X5 in Russia which has similar self checkout cameras and they do use this for identification. And recently ASDA and other Supermarkets have partnered with Yoti (a UK digital identity company) to use their checkout cameras for age verification, https://www.yoti.com/blog/yoti-digital-age-verification-tria...
Imo it's clear where this is heading regardless of what it's being used for exactly today. And it's possible they might already be using these cameras to identify previous problematic customers, but I might just be paranoid. I don't think anyone really knows what individual supermarkets are doing with them today and no one really seems to care either.