A Large chunk of those went to wages paid to soldier.
A private in Russian army paid around 50000 Rouble a month. That's about 830 USD (or 800 Euro) a month, Russian have (Or had) around 300,000 (Starting with 200,000 and then put another 100,000 in May) Let's say all of them are private, the total wages are about 1.5 billion. Then you have NCO, Officer, Sign in bonus, Wagner Group, Other paid help which paid multiple times a private, conventional estimate would put the number of wages paid to all group about 50 billion in this war.
Then you have death benefits, fuels, food, lodging, to pay for those people. Then you put in equipment lost, perishable (like munition and such) each dumb bomb alone cost around 2000 USD, each 152mm artillery shell cost around 200USD (US shell cost around 400/per), the Russian military had expanded multiple millions of those shell, then you talk about missile, and hypersonic missile used in this war, and the equipment lost and captured by Ukrainian, a tank will set Russian back several millions, and Ukraine had captured around 160 confirmed by Open Source. Moskva alone cost 750 million in today money, along with a few transports ship lost and tugboat, Helicopter and fighter jet,
They probably had lost around 20 billion a month in the lower scale.