It still looks like this to this day, you can find it in any grocery store

Uhh, I was born there :)
Also, a lot of household stuff makers just continued making products with oldschool packaging, because it was easily recognizable. So if in the USSR you had THE condensed milk in iconic packaging, now you would have many condensed milk brands, but most of them having some kind of variations of the og package. I even have a magnet with it