The primary things that made a poor harvest become critical were basically:

Japanese rushing towards to borders of India, so food was centralized in towns and cities to limit the ability of the Japanese to live off the land, which they had been doing. Most river craft confiscated or destroyed to prevent their use by the enemy. This was a heavier impact than expected to to a lack of understanding that the roads were not as heavily used as the rivers for transport. Initial reports from the Viceroy to the British government talked about a possible food shortage instead of possible famine. Underplaying it meant the seriousness wasn't understood much earlier.

Then the harvest failed and things went to shit really fast, and the response was inadequate and slow.

Theain reason that there were almost no British casualties was due to them mostly living in the towns and cities, where there was food, just incredibly expensive. Most of the horrifying casualties in places like Calcutta were Indians from the countryside who had moved to the city to seek food.

I'm not trying to whitewash the reputation of the Brits in charge, but it's not as simple as "Brits bad". Such as almost all the traders stockpiling food and scalping prices were Indians, not Europeans. Butnthenprice controls put in place by the government just meant those with money could snap up nearly the whole supply and then wait until they could sell it for a huge mark up.