>>3
Thanks for those videos! How odd to see Vietnamese "Nu, pogodi" sequels! I assumed those 4 videos weren't originally widescreen (they were for TV, weren't they?), so I viewed them through the DIY page here and set the "Adjust aspect ratio" to "0.75" to get the correct width.
Yes, I can see the resemblance. Though I don't think the animation style itself was influenced by the Soviet Union, just the characters! The weightlessness and really loose drawing style also reminds me of the early Georgia Film animated films from the 1930s and 1940s (although those had a higher budget). Like these ones up on culture.ru:
https://www.culture.ru/live/movies/19066/argonavty-kolkhida
https://www.culture.ru/live/movies/19058/proidokha-khitraya-lisica
https://www.culture.ru/live/movies/19065/yunyi-strelok-voroshilovskii-strelok
https://www.culture.ru/live/movies/19064/chiora-dostoinyi-otvet
And this one on Animatsiya (the earliest one on this site currently)
https://www.animatsiya.net/film.php?filmid=878