I know for a fact that it’s mandatory for people who reside in the US (citizens, visa holders or those with a green card) but does that also mean foreign visitors (like those from Mexico, Canada or EU) have to complete the census too when they are on US soil? Have you visited the US during a time a nationwide census was taking place as a foreigner (alien)? If so, do you have to answer the questions present on the census even though you do not live there?
They don’t care about having a list of non-citizens to harass – they just do that based on skin color.
What they care about is having a mechanism to force an undercount in blue states, so they can get red states further disproportionate power in the House and electoral college.