They're just on a prepaid card program provided by IDT Financial Services (if scroll to the bottom you can see it listed).
Same company that provides prepaid cards to Osper.
There's a half dozen prepaid card providers in the UK.
There's also Marqeta in the US (used by doordash to by food on your behalf) who they could have used also well as a dozen other prepaid card providers.
They just made it hard for no reason.