Slop.

It is in fact several things. In general we speak of two things, both having formed their identity in opposition to Russian communism.

There's Dutch/German left communists, who Lenin was mad at because they disagreed with him on how to do communism (For instance, many were unwilling to compromise their positions to participate in or engage with bourgeois politics, which Lenin considered childish) and who were mad at Lenin for doing communism wrong (A huge one was centralising power in the party instead of devolving power to the sooviets, in their view betraying the revolutionary mass movement embodied by the councils). They then started doing their own theoretical work in parallel to developments of marxism-leninism.
Several movements arose from this line, like council communism, situationism, and autonomism.

Then there are Italian style left communists, or bordigists who believe that Lenin was right in his criticism but also you should never, ever, ever, ever, ever, ever, ever do any kind of political organising, and also all of them get weirdly cosy with right wing political stuff but that's surely just a coincidence and has no bearing on the movement. (Except it's not a movement because that implies doing something). These guys basically only exist on the internet, their main thing is telling you they know how to do communism better than you and it's by not doing anything.