They were and are truly attempts at building communism. They were "true communism" in that sense. At the same time, they have yet to reach the stateless, classless, moneyless society stage where production and distribution is fully collectivized and oriented towards satisfying needs that communists call "communism" as a mode of production.

The "not true communism" argument more refers to those that incorrectly deny the USSR, PRC, Cuba, Vietnam, etc as validly socialist states working towards communism, not those that acknowledge them as genuine.

You literally said:

Socialism, probably yeah. But here it's communism thats displayed

That person explained why that's a flawed way of understanding previous socialist experiments and that the distinction you're making doesn't make much sense, and instead of listening and admitting you don't know much about the topic you decided to accuse that person of a logical fallacy that doesn't even apply.

(Looks like the comment I replied to got deleted, so mind the context was in response to "Not true communism TM")

This is an ignorant way to respond, although I can appreciate these terms have several meanings that can be difficult to follow.

Communist parties of the 20th century knew and openly stated that what they had built was a socialist system and communism was the endgame. The goal of 20th century socialists was to gradually progress to that point that scarcity is abolished and distribution follows the principle of need. At which point they might declare communism achieved, so long as other things have happened like completing the (gradual) dissolution of the state.

It is not an attempt to distance from a bad word - we/Marxists/Communists don't see it as a bad word.

And the 20th century movements & their states were "real communism" in that they were a genuine expression of the movement for communism, and furnish us with both positive and negative examples.