Explanation
The losses of Germany on the eastern front are widely believed to be the most significant factor in defeating Nazi Germany and the USSR won the battle of Berlin, the final battle before the German capitulation. Thus Europe widely believed (for a good reason) that the USSR was the main contributor in defeating Germany. With the cold war the perception of the USSR became a lot worse in western countries like France and with increasing anti-USSR sentiment the view flipped to viewing the USA as the deciding factor. The USSR (and the Russian Federation today, even if its government is very anti USSR) viewed itself as the most important force in defeating Germany, especially because the USSR had the biggest amount of deaths. It is worth noting that the USSR was at least commercially allied with Nazi Germany until June 22, 1941 and there was an agreement between the nations on which parts of Europe each could invade and which where reserved for the other.
Poland had invaded these territories in the Russian Civil War and annexed them, as you see on one of the maps I provided those territories had ethnic majorities of Belarusian, Ukrainian and Lithuanian peoples at the time, what makes you think they were Polish territories?
They were Polish territories because Poland held and administered them. They were also part of the PLC before the Russian empire seized them...
https://en.wikipedia.org/wiki/Partitions_of_Poland
We can argue all day about what conditions grant a right to a territory. Or we can cut the bullshit and stop pretending that the Soviets sending the Red Army across the Polish border to conquer land, while raping the inhabitants, was anything but an invasion.
And that's where we stop arguing. There is no evidence of higher rates of sexual assault by Soviet troops than by any other, and the whole "rapist hordes" stems from Nazi wartime propaganda and has been picked up by racists like you. You stop being able to defend "polish ownership" over majority Lithuanian, Belarusian and Ukrainian territories by ethnicity when confronted with evidence, and resort to racist Nazi propaganda of "rapist hordes".