750K Indians have given up Indian citizenship in the last 5 years

Around 150k per year formally relinquishing Indian citizenship, which may be almost fully accounted for by US, UK, Australia and German immigrants formally renouncing their Indian Citizenship (India does not allow dual citizenship and requires people to give up their Indian passports in exchange for permanent travel privileges to India: https://www.cgisf.gov.in/page/general-information/).

In other words, nothing new. The 25k per person is almost certainly an underestimation: its much more likely to be 50k or above, and India would not have gotten any of that anyway, whether the emigrants gave up Indian Citizenship or not, and pales in comparison to the orders of magnitude higher number of emigrants who have chosen a country other than India to build their futures and produce economic value. Too bad, but people are the primary export of high-population countries such as India, China, the Philippines, and so on, and "loss" of GDP is the normal consequence of that.

immigration can be observed as a form of colonial extraction, taking the (human) resources from the periphery, to the core of empire. Thankfully India is big enough to sustain small loss of population. Peripheral countries in Europe though - Bulgaria, Romania, Greece even - lost huge volumes of the youngest and most talented. Latin America to North America another pathway for the flow of these resources

I feel this is very normal for a country of the size of India.

The good part is it is way less as compared to China