Most of the dead were legally citizens of the Russian Federation, but not what the leadership would really consider "Russian". To them, only people in the core Moscow - St. Petersburg region really count. Others are expendable. They may even see it as a net positive to purge some of population from the outer provinces: drunkards, unemployed, criminals, members of ethnic minorities, etc. (To be clear I don't support the Russian invasion of Ukraine, just explaining what Putin and his key supporters seem to be thinking.)

At WWII, Russian interrogated their own Russian villagers about what Germans did, and then murdered the interrogated Russian, for the chance that Germans later asked him what he told to the Russian army.

The large count of Russian deaths at WWII is in large part due to communists killing civilians and then blaming Germans or the war.

The thinking hasnt changed since Stalingrad, where civilians could've been evacuated and Stalin decided not to to help absorb the impact of the incoming army. Expendable.

It's just a shithole country.

Inb4 "Russia isn't the USSR" - yes it is.