I kind of figured that was the case given it was released in the DDR.
Actually it's apparently famous as a crucial part of the DDR's hagiography of Thalmann and was required viewing for East German workers for years. There's more detail in the Wiki Article of the film:
https://en.wikipedia.org/wiki/Ernst_Th%C3%A4lmann_(film) which also mentioned there was a second part, concerning the events of 1930-33.
If you're still interested in watching it (the combat scenes are pretty much mostly what you see in the trailers), there's an option to auto-translate to English (or any other language). I mean, it's a Reds vs Reactionaries film and the history is very well-known (even if the film is, ah,
massaging it), so I was getting the gist of it even in German, but the English subtitles aren't too bad.