It was actually fairly equal, with Russians making up around 60% of the SovUnion's population and 60% of the Red Army.
Ukrainians were around 20% of the SovUnion's population and 20% of the Red Army, but much of Ukraine was under Nazi occupation - thus, Ukrainians of military age still under Soviet control necessarily were drawn from more heavily or volunteered more readily to get to 20% of the Red Army.
Who wants to tell the one guy that the people who did most of the fighting in WWII were Ukranian?
It was actually fairly equal, with Russians making up around 60% of the SovUnion's population and 60% of the Red Army.
Ukrainians were around 20% of the SovUnion's population and 20% of the Red Army, but much of Ukraine was under Nazi occupation - thus, Ukrainians of military age still under Soviet control necessarily were drawn from more heavily or volunteered more readily to get to 20% of the Red Army.