Gazprom Russian majority state owned multinational energy corporation was created August 8, 1989 in the final year or so of the USSR (Soviet Union).
It transitioned intact to the Russian Federation on the final day of existence of the USSR, December 26, 1991.
I would be correct to display both the flag of the USSR and the Flag of the Russian Federation at an event or conference by Gazprom.
You are correct.
But why the Russian Imperial Flag?
I remember a few years ago, at a lot of European soccer games, you would see advertising for Gazprom everywhere.
Flying the Communist USSR flag is no more appropriate that the Nazi flag.
Except for communist pos.