The default should be to treat people with respect and give benefit of the doubt until proven otherwise, treating people as guilty because of where they were born is always a crappy thing to do.

Given that the EU after over 3.5 years of full scale invasion still buys Russian oil, should we also treat EU citizens as sponsors of the war?

Judging from this logic you would have supported the US locking up the japanese people in internment camps right? If not, why not?