You may wonder, but computers extremely important in our life, I bet, you don't release how we depend on high tech now (was not such before war).
I will list how I remember, not by importance.
1. Electric grid is core of infrastructure, and it depend on computers. Even if in many cases could use decentralized power sources, but need it to feed bank networks for money payments; water supply, heating, also need electricity. And Russians actively use hacker attacks to turn off power in Ukraine.
2. Air defense. God bless America and developers of Patriot! After last spring we received this wonderful tech, we could feel much safer, just periodically hear "Citizens may hear explosion, as system automatically intercept ballistic missile. Alarm siren was not triggered".
3. For our people in trenches, information is literally life, because Russians have large number old, but dangerous tech, like artillery and air approx 1960s. And now also got cheap new tech from East - most annoying drones (UAV).
So if one side got knowledge, where some opponent military unit, they immediately fire on it if possible.
Even become usual thing, artillery duels, when artillery units on each side, try to destroy each other. And as they are long distance units, they don't see opponent, just know from intelligence, that on some coordinates appear opponent.