depending on who youre talking to it either means all communist or specifically communists who unabashedly support authoritarian sociopathic governments
communists who unabashedly support authoritarian sociopathic governments tend to frame it as exclusively an insult for communists in general, either out of a refusal to recognise any other branch of communism as actually communist, to pull attention away from their support of authoritarian sociopathic governments or to frame whoever is calling them tankies as anti-communist, and probably a fascist
the only thing twitter is still good for is art and porn, so i use it for art and porn