UK non-dom status, US citizenship taxation, Irish corporation tax, etc. are all tax rules that benefit that nation at the expense of globally fair taxation. It would be interesting know how Mrs. Sunak is taxed in India - does she pay like a local or does living in the UK give her a break?
Not sure what taxes in India she pays on her income in India but apparently a big advantage in remaining domiciled in India will be avoidance of inheritance tax since India does not have an inheritance tax.
The top income tax rate in India is 30% so a very big saving there as the top rate in the UK is 45%, and she got over £11.6m in dividends from Infosys last year. (Dividend tax rate is a little lower for those in the additional rate band - 39.35%, and she does get the first £2,000 of dividends tax free)
Higher rate £50,271 to £150,000 40%
Additional rate over £150,000 45%
In India, the 30% rate starts at ~£15,000. Not sure if India has a different rate for dividend income