This seems unlikely given the population disparity between the Russians and Ukrainians (which was similar then as it is today) and the casualty figures. I can’t find actual estimates of the ethnic breakdown of the army, but there are breakdowns of casualties by SSR. Obviously SSR is not a perfect analogue of ethnicity, but the numbers are far enough apart that I think it does the job here. Roughly 65% of military casualties were from Russia, 15% from Ukraine. Ukrainians were one of only two groups to be overrepresented as a proportion of casualty figures relative to their population though, the other being Belarusians.
This seems unlikely given the population disparity between the Russians and Ukrainians (which was similar then as it is today) and the casualty figures. I can’t find actual estimates of the ethnic breakdown of the army, but there are breakdowns of casualties by SSR. Obviously SSR is not a perfect analogue of ethnicity, but the numbers are far enough apart that I think it does the job here. Roughly 65% of military casualties were from Russia, 15% from Ukraine. Ukrainians were one of only two groups to be overrepresented as a proportion of casualty figures relative to their population though, the other being Belarusians.