But not all these soldiers are war criminals

They literally are war criminals. They're participating in an invasion for no cause other than boosting Putin's ego.

And I've seen the propaganda advertisments in Russia "Go to war, support your country" and "Go to war, gives good money, support your family" and such.

Invading another country without cause makes you literally a war criminal. It is really ... that simple. Russia is literally a terrorist state at that moment. They've killed hundreds of civilians, thousands of Ukrainian fighters as well. Putting mines all over the place. Crippling and injuring so many other fighters and civilians as well. Sent terrorist groups.

If you're participating in such war, you are a war criminal. You can kill yourself. you can abandon your unit. You can bribe your commanders. You can run away before all this even starts. But by the moment you're invading another country and you're killing innocent people who have done NOTHING to you, you're a war criminal. It is really ... that simple. Coz it's "either I save myself or I kill these innocent people". That's a war criminal mindset coz it makes it seem as if you're a good guy in your mind. When you're not.