You are right that the Russians have been frequently somewhat mistreated in the former Soviet Republics where they have become minorities.
However, this is an extraordinarily hypocritical claim, because this has followed a time when for various durations, between a half of century and two centuries the Russians have mistreated the minorities of those places in a much more ferocious way, inclusively by robbing them, murdering them or sending them to forced labor in Siberia.
In Ukraine, there are many places with Russian colonists who have been installed after WWII in the houses that before the war belonged to various other nationalities, which were then killed or dispersed to Siberia by the Russians.
Yes, Russians have been mistreated after the separation of the Soviet Republics, but this is much, much less than what their fathers have done around WWII and before it, and many of them have still inherited what their fathers have stolen from the other nationalities.
Had the Russians treated better the others when they had the power, they would have not been so hated, so they would have been much more likely to be treated correctly.
That's missing the point.
When a toddler does something inappropriate, "but he did it to me" is not an excuse. If both kids did something bad, I want both to apologize, and both to move on. It's also not a contest for who did something worse. I want Ukraine to apologize to Poland. I want Poland to apologize to Ukraine. I want both nations to move on.
Two wrongs don't make a right.
Indeed, that's doubly the case when it's nations -- a civilian hit in a retaliatory strike often has nothing to do with an atrocity. I don't know where you are, but I'll pretend the US. If someone whose father died in Guantanamo, or whose child was killed in an airstrike in Afghanistan, killed your mother, would they be "right"? Would it be hypocritical of you to complain?
Or if you want to punish a dictator, does it make sense to starve the people in his nation -- most of whom probably want him out even more?
I am perfectly aware of all of Russia's wrongs. You missed most of the big ones, from holodomor, to about a half-millennium of other torment of people in Ukraine.
You try to do right for your own soul. Apologizing doesn't weaken you.
And you don't punish children for the sins of their fathers.