It means whatever it needs to mean in the context in which it is deployed.
It's a tool deployed by liberals against people to the left of them in exactly the same way that woke is a tool deployed by reactionaries against people to the left of them.
It gets deployed against everything from ML to anarchist to even socdems, depending on whether you say something that goes against the US' imperial core goals.
The purpose of the tool is thought-termination. To prevent people from listening to the person that it is deployed against. Reactionaries use woke to prevent people among their ranks from listening to anything reasonable the ""woke"" person might say, and liberals use tankie to prevent people among their ranks from listening to anything reasonable the left might say.
It is an adaptation of mccarthyite behaviour.
You ain't done nothing if you ain't been called a Red applies now to this word just as much as it applied back then.