This, for me, was the most important aspect. To mandate that a substantial swathe of British citizens can only maintain citizenship if they meet a Govt’s criteria of what constitutes ‘good behaviour’ is simply wrong.
This is a far bigger concern than Begum herself.
It must be absolutely huge swathes of the population. 7m people are eligible for an Irish passport so they could have their British nationality taken away. A quick google shows there's ~10m people here who weren't born in the UK.
By the time you've added in second generation immigrants who'd likely qualify for nationality of their parents home country, it's probably over half the population who can have their citizenship snatched away.