Born in UK and think her parents were british at the time. Wiki article doesn't have history of her parents and I can't remember the history so can't say for definite. As far as I know british from birth. https://en.m.wikipedia.org/wiki/Shamima_Begum She isn't a sympathetic case against principle of stripping people of British citizenship when they have secondary citizenship and arguement in her case is whether she has another citizenship. If only have british citizenship then can't remove it. If have more than one citizenship then first to remove it wins and owned by last country standing. Bangladesh isn't admitting to owning her and probably be subject to death penalty if in their custody. https://www.bbc.com/news/world-asia-48154781.amp Her history won't win her any friends and probably divides people depending on whether troubled by principle of stripping citizenship (and abdication of responsibility for dealing with former citizens) and those that look at her and think bye. Wrong case to decide legal principles as won't be able to remove emotions. Interesting case in that for those who have claims to more than one nationality then can have nationality removed at home secretary discretion. Real question is what are standards and protections.
I think she had her british citizenship removed as a cop out. Has she been accused of anything in the UK? If so..isnt she entitled to a fair trial here ?
She is duel citizen by her father ( Bangladeshi although this is disputed) and can be stripped of British Citizenship if the UKGOV believe her actions may cause harm to the UK