I have a very different experience. When Hexbear was still federated with the large instances it was total mayhem. They would turn every thread political, constantly spam images of dictators like Stalin and Mao, and swarm anyone who disagreed. I've seen them deny the wrongdoings of China and the Soviet Union quite often, which is probably also what's necessary if you spam Mao and Stalin unironically.

I'm quite left of center myself, at least relative to most people I know in real life. But these people seemed totally insane. It was probably also a numbers game, since Hexbear was relatively large at the time compared to basically every other instance. So maybe this was just an annoying minority. But nevertheless I'd never purposefully go there, and I'd recommend anyone to stay away. It's way better than for instance a Trumpist/far-right instance, but I'd rather avoid both.