Revoking someone's citizenship is not a recognised legal punishment. It's purely political.
According to recent UK legislation, UK acted lawfully, but according to longstanding international and UN laws, they didn't, despite UK being a longstanding signatory to such laws.
As said, citizenship has become a political and hierarchical decision based on your ethnicity and the origin of your parents.
I believe I'm correct in stating that only Muslims and Black people have been deprived of citizenship. Therefore the revocation of citizenship is based on UK's colonial past, and its continued attitude towards second and subsequent generations.
It's also based on gender discrimination.
You're still basing your arguments on the denial of another country's right to interpret its own laws.
Bangladesh have a right to determine its own decisions, not have them forced on them by UK, by being put in an invidious position.
Bangladesh stated at the time that Shamima was not a citizen, neve had been and would be denied that right if she applied. Moreover they stated that should she enter Bangladesh, she would be subject to the death penalty if convicted of terrorism.
There is a vast difference between a voluntary act and the denial of someone's human rights.
Statelessness means denying someone their basic human rights:
Today, millions of people around the world are denied a nationality. As a result, they often aren’t allowed to go to school, see a doctor, get a job, open a bank account, buy a house or even get married.
https://www.unhcr.org/uk/ending-statelessness.html
If someone voluntary chooses that status, that is a freedom of choice, which is vastly different to having statelessness thrust upon you against your will.
You're conveniently narrowing down the arguments to exclude the argument that revocation of UK citizenship is hierarchically based on one's ethnicity and gender.