Regardless, I prefer the base game communist flag. Looks more specific to communism and not the general left

It's not the flag of Alaska in the other mod, it's the Starry Plough flag: https://en.wikipedia.org/wiki/Starry_Plough_(flag)

It was used quite frequently by left-wing Irish republicans in the 1930's and it's the flag of the Irish Republican Congress: https://en.wikipedia.org/wiki/Republican_Congress

The other flag he uses is also historically correct, it was the flag of the Blueshirts/ACA, the fascist Irish paramilitary group active in the 1930s: https://en.wikipedia.org/wiki/Blueshirts