alt Hacker News> - Ukrainians are the second largest ethnicity in Russia.
No. Never was. https://en.wikipedia.org/wiki/Ethnic_groups_in_Russia
> - Russia got the majority of Ukrainian refugees since the start of a war if we count per country.
No. https://www.statista.com/statistics/1312584/ukrainian-refuge...
You might be confusing abductees with refugees.
> - The majority of people living on a currently contested territories of Ukraine used to be USSR citizens.
The majority of people living on contested territories of United States in 1775 used to be British citizens. So?
> - And yes, if Ukraine is using cities as fortresses and do not evacuate civilians from there, high chances are that after weeks and months long battles those civilians end up in graves with nasty wounds on their bodies.
Absolutely vile propaganda.
I agree with what you say, but "Never was" is contradicted by your Wikipedia link, which shows Ukrainians in the second position at the 1926 census, being overtaken by Tatars in the more recent censuses.
However, it is not said which is the territory for the 1926 census data, it may have included a part of the present territory of Ukraine, because the borders of present Ukraine are very different from the borders of Ukraine after WWI.
Such census data about Russia and the Soviet Union are hard to interpret without precise knowledge of the corresponding territories, because the fluctuations in numbers may be unrelated to natural growth, but determined by administrative reorganizations or forced deportations.