The upcoming federal census is an "enumeration" not an interview.
But do not take my word for it. Read the United States Constitution yourself.
The federal government recently said that a census "interview" is constitutional. The federal government also thinks printing trillions of dollars out of thin air is constitutional. Maybe you should demand that the people you vote for actually read what they swear to protect.
"How many?" should be the only question you hear after the federal knock on your door.