You first gather the data while people don't know or care. Then you weaponize it later. It happened at least once not long ago in another country, seems not overreaction to be concerned about it
It happened a year ago in this country, with IRS sharing data with ICE (breaking a longstanding policy of keeping taxpayer data private within the government).
If this is a Nazi reference, Census data was used to send people to concentration camps here during the same era. Less awful than death camps, at least.