YC has definitely backed some shady shit in the past, but I suspect these guys might just be straight-up fraudsters.

They claim to be backed by several major investors, but I can't find them in YC's startup directory [1] or Antler's portfolio page [2]. Their website also doesn't have any of the details you would typically expect from a legitimate business, such as an about us page, a description of their corporate history, or an office or mailing address.

1: https://www.ycombinator.com/companies 2: https://www.antler.co/portfolio