Remember she has a state just not the one she was brought up in, so I'd consider correcting your post
Whether she is stateless or not is up in the air. The BBC, Al-Jazira and the Guardian have all referred to her as stateless this afternoon or “effectively stateless”
A UK tribunal accepted arguments by UK lawyers that she had Bangladeshi citizenship before turning 21, but ultimately the only authority on who is and isn’t a Bangladeshi citizen is the government and courts of Bangladesh and they have been unequivocal that you have the right to Bengali citizenship if your parent is born there, you don’t automatically have the citizenship.
I can only imagine how some people in this country would react to a foreign government dictating our citizenship laws and telling us they were wrong.
Anyway, if major reputable news publications are happy with calling her stateless then I am.