I decided to give Mastodon another shot here recently, I found exactly one promising leftist instance, mastodon.lol. Bills itself as an "LGBT-friendly antifascist mastodon instance"
I watched another user get banned for saying that Azov were neonazis and I got banned for sticking up for them, then as part of his 240V power trip the admin posted a pity thread where he claimed we called him literally Hitler.
The only other leftist instance I saw welcomed all socialists except "authoritarians" so I assume it's either a socdem or sectarian anarchist instance.
TL;DR - Mastodon hasn't changed at all, it's still ran by power-tripping micro tyrants
TY I'd appreciate that. And yeah, moderating one site is more than enough work
Okay so at a glance the only explicitly Marxist one I can find is tankie.ml, which is a BookWyrm instance, not Mastodon or some other microblogging service. It federates with activitypub, but not really what you're looking for.
I am finding open communists on these sites tho:
update: i asked the admin of tankie.ml and they also suggested
monads has had quite a few struggle sessions on the network from hosting "tankies" (they usually responded that they find other instances have a habit of being racist towards them). I think they're pretty close with octodon.
yeah, same admin, a lot of the same users