Can someone explain like what are the lemmy devs political stance ?
They're tankies, ie radical communists who support authoritarian regimes like North Korea and the CCP, and fully support Russia's invasion of Ukraine. The devs also onboarded someone who openly said many times on October 8th that "all Israelis are valid targets", "anything that moves and isn't Palestinian is a valid target" and "there's no such thing as an Israeli civilian" and he's still in their team. On their own instance lemmy.ml (their choice of the .ml TLD is a reference to Marxism-Leninism), if you mention the Tiananmen massacre you get banned for "orientalism", and if you say that Hamas are terrorists you also get banned for "bothsidesing (sic)".
Does that leave a stain on Lemmy, the open-source project? Yes, for sure, it leaves Lemmy with a very questionable governance, and weird decisions like the absence of any prioritization of work on moderation tools and the very weird and completely random fact that they suddenly disabled sign-up captchas last summer leading to a bot infestation of most instances. Coincidentally, tankie instances like lemmygrad and hexbears rely on brigading, bots, and cyber-harassment to spread their poison, and strong moderation tools would hinder them a lot.
Now does that make it impossible for Lemmy to succeed? No, it's again an open-source project, and it can be forked away from the tankies at any time. In fact, there's even a highly credible rewrite in Java currently whose goal is to be 100% API-compatible with Lemmy: https://sublinks.org/ (see the announcement here: https://lemmy.world/post/11005411 )