If the west would stop vilifying people of different skin color and continent of origin, we'd realize that humanity as a whole does not have that much of a demographic problem. "We are too many" as an argument to keep borders closed and "we are too few, get more kids" are incompatible arguments, unless people are honest about racism.
Humanity as a whole has a demographic problem. A few countries are just outliers (being still quite above > 2.1), but nowhere enough to offset anything at a global scale, and besides, they're on the decline too, just earlier in the curve.
Second, caring about your ethnic culture is not the same as "vilifying people of different skin color and continent of origin". It's just not treating nations as comprised of interchangable consumer/worker units whose shared culture and history (or lack thereof) doesn't matter.
Most countries have a long history tied to a culture created from one or a handful of ethnicites, they're not just pieces of land for settling associated with a civic contract, like the us has been (and of course even that came at the erasure of the native cultures and populations).
Nobody talks about individuals or people as arbitrarily interchangeable units. That's a populist exaggeration.
The "natural state" of a culture and an ethnic group is the continuous exchange and intermingling with other cultures and ethnic groups. It's a success of the nationalist right to make people believe that it's the opposite.
Given that we're in a huge democraphic crisis which will bring untold disaster and misery, a huge depression crisis, marriage crises, and a loneliness epidemic, perhaps we're not the best arbiters of whether they've been proven "necessary" or not.
As for the questions, to some degree they indeed do, so partly yes, but also those differences in treatment are not on a case by case basis, but on average.