Probably some sort of berry or fruit pudding that were very popular (and some still are) also here in Nordics around that time. It's a sort of jelly with cream on top, that's what it looks like at least.
Could be, but here next to the USSR in the 80s the factory and work lunches did look pretty similar and usually had some berry jelly thing or such included, not every day. But it was not that big typically.
In most places they still do, that lunch on tray style work food still looks a lot like this today, at least here.