They want Belarus isolated. It's ideal (for Putin's Russia) that the EU and US crack down harshly on Belarus, isolate them, and drive them into Russia's arms out of desperation. Lukashenko has been resisting a union with Russia for some time and using the West as a hedge, a way to create at least the illusion of an alternative to Russia's arms. With that gone, his options dwindle significantly, which is what Russia wants to see happen. There is nowhere else to turn, and few allies, other than Russia.

If you're Putin, what you want in this context, is for the economy of Belarus to get smashed to pieces, and Belarus to get entirely isolated politically in regards to the West.