While 75% speak Russian in Donetsk, only 40% are Russians. Do not confuse language with ethnicity. The majority of Irish speak English. The majority in Donestks are Ukrainians.
If that’s true, then those majority Ukrainians voted for separation in 2014. Since then they’ve been subjected to 24/7 shelling from the UA which has caused approximately 14,000 deaths. One must assume that over half of those victims are Ukrainians then.