Is it odd that India declared a day of state mourning for the British Queen?

Flags were lowered on Sunday and there was "no official entertainment".... not quite sure what that means.

The Indian PM wanted to convey his respects to the passing of the queen but many Indians were infuriated, not just because of the fact they were brutally colonised by Britain but also because the Royal Family still hold a number of treasures taken from India including the Kohinoor Diamond.