I guess, depending on how it's implemented, maybe an ID could be cloned and still appear valid, but that seems like a possibility for the UK's approach as well (the clone would just point to the same database entry).
But considering that they've been retiring things like biometric residence cards in favour of web-based systems, it's possible there will be no physical component.
Now they want to make it illegal for employers to illegally give a job to people it was already illegal to give a job to by making them have a new ID, when it was already illegal to give someone a job without getting proof of their right to work in the UK!
You are 100% right
Really? If anything it would make them easier. Hackers routinely break into government databases to exfiltrate information. An ID attribute databases would be no exception, for exfiltration, or simply modification of data. Ie: creating a fake ID.
We have this is NSW in Australia: the Services NSW app provides a digital drivers license which is guaranteed to be accepted by authorities as legitimate.