The single caveat I'd add - and I have absolutely zero statistics with which to back up any population % figures or cultural analysis - is this: clearly there were a LOT of Russian citizens who, when the Soviet Union collapsed in 1991, found themselves suddenly living in what became the independent sovereign state of Ukraine. These were Russian workers who transferred to the Donbas region because of the wealth of mining, resource extraction, and manufacturing jobs that existed in this area that needed workers to fill.
"(In) the good old days, when Donbas was hailed as a “Soviet workers’ paradise”, its blue-collar residents, especially coal miners and steelworkers, enjoyed hefty salaries and plenty of perks. They had free healthcare, free education and dirt-cheap vacations to Crimea or even the “socialist camp,” or Moscow-friendly nations of Eastern Europe – Bulgaria or Poland. Hundreds of thousands of people flocked to Donbas from all over the USSR – and mostly switched to Russian. The 1991 Soviet collapse was painful and disorienting to the USSR’s 287 million of its denizens, but it hit Donbas especially hard."
How Ukraine’s Donbas has ‘evolved’ under pro-Russia separatists
So these were Russian citizens, spoke Russian, had family in Russia, and thought they were just moving to a different region of the Soviet Union, and when it suddenly collapsed in 1991 they were no longer in Russia. And they weren't happy about it. "By the time of the Soviet Census of 1989, 45% of the population of the Donbas reported their ethnicity as Russian. In 1990, the Interfront of the Donbas was founded as a movement AGAINST Ukrainian independence."
These are same "Russian Separatists" who have welcomed Russian annexation of the Crimea and have advocated for Russian annexation of the Donbas. They've actively been fighting a civil war with the Ukrainian government since 2014.
Given current circumstances, if the Russian Federation offered these people a relocation package back to Russia I have every expectation that - to escape a war zone and given the destruction of their homes and factories, etc., and possibly the inevitable recognition that the territory belongs to Ukraine and - barring Russian annexation - will one day be Ukrainian again, these people very well may be volunteering to be returned to Russia with their families and neighbors, etc. And they collectively constituted some 45% of the entire population of the Donbas and Crimea.
I'm positive that Ukrainian refugees are caught up in the exodus as well, and probably have been relocated against their will - except that currently they are out of the war zone. But I'm also positive that a huge percentage of the population flow into Russia likely consists of Russian Separatists who are tired of fighting in Ukraine, recognize that the Donbas will be a war zone into the foreseeable future; and simply want to be Russian citizens again living in Russia. So they accepted the relocation package. Russia is certainly "stealing" some portion of that population being repatriated to Russia - but the percentage of that population who want to return to Russia is probably quite high as well.
No mention of the fact that a few Russian made famines killed off most of the Ukrainians in the area so Stalin to keep the farms working repopulated the area with Russians who took over the empty farms and houses. They often had to move the bodies out of the houses before moving in.