The worst beer I ever had was Moskovskoye (Muscovite) beer, which I had when I visited the Soviet Union in 1972. It was just about the only available, and everyone drank it warm.
The better eateries offered Stella, an Egyptian beer, which was a lot better. We figured the Egyptians were exporting beer to the Soviet Union in exchange for the vast amounts of military aid they were receiving.
I had some horrific beer in Ukraine. Can't remember what it was called but it came dirt cheap in 2 liter plastic bottles like soda. Just awful stuff.
I’ve had Russian beer (obviously in more recent years) and it was as good as any Eastern European beer.