What do you consider "far left"?

https://en.m.wikipedia.org/wiki/Twitter_suspensions

This link answers my question - thanks.

Far left is the opposite of far right, for which we can all point to many of them that have been banned from twitter.

I'd define the far right in terms of distance from center, personally.

So, I'll refine my question with an example from the list: who is the Anders Breivik of the left?

well helping people is the opposite of killing them so maybe a meals on wheels driver or a public defender?

Which far leftists do you think have done things on twitter similar to what caused far rightists to be banned?

I think the framing you're proposing is off; what the right has done are things that are offensive to leftists and as a result they're banned. It's tautological. This is exactly the premise of the criticism levied in this thread and writ-large at Twitter censorship.

Casual racism directed at white people is common and goes unpunished, for starters.

Who’s been banned for racism?

Nick Fuentez (well, racism and antisemitism), David Duke, I'm sure there are more but these are the only examples I know off the top of my head from being terminally online