Considering it's still dead simple to become inundated with far right opinions and conspiracy theories on twitter, it's a bit of a stretch to claim it's "left-twitter."

Just because the most egregious and dangerous stuff from one side gets deleted does not mean it's a place only for the polar opposite.

Ive found Twitter leans left by about a ratio of 10 to 1.

However the volume of users is sufficiently large that you can be swamped by any minority if you choose, no matter how tiny.

“left-twitter” simply designates a subcommunity within twitter. I don’t think OP meant that Twitter as a whole leans left. Many people have an opinion on that topic, but in reality it’s hard to know for sure as Twitter is very large.

Twitter has a lot of community subsets, so you're right. We can also see what it looks like on reddit.