The effect of one's culture and surroundings changing will naturally be anxiety. Consider a proud ethno-cultural place like Iran or Japan. If a large number of non-persian or non-japanese people began moving into each of those respective countries, the result would be anxiety among the established majority.

Similarly, it's really just a natural human response that people of European descent are experiencing anxiety in their native countries when faced with large scale migration.

I think that a lot of people are unwilling to give sympathy to Europeans because of the recent history of European colonization across the world.

But it's not some failing of white people in particular that they in some cases may have anxiety about their communities changing. It's just a result of the human condition, human social behavior. As such they do deserve sympathy. Just like the hypothetical Iranians or Japanese in my prior example.