You can review blocked instances here:

https://lemmy.world/instances

As for why? You’re absolutely right, this is often over political issues(drama, censorship, values, etc), sometimes technical ones, and there’s no guarantee that your instance’s mods goals are aligned with yours. In a healthy instance, you can search for the name of a blocked instance and find a relevant post about why it was blocked.

There are also blocklists: https://gardenfence.github.io/ I don’t know offhand if Lemmy.world makes use of them.

You can, of course, go to the blocked instance as a guest, to investigate or validate your mods’ claims, but a blocked instance will not shoot up on your page.

I made the mistake of replying to someone in Chapotraphouse once, something I considered fairly innocuous like Biden had done better than my initial absolutely zero expectations for him.

What followed was a hailstorm of WEEKS of replies with the most batshit insane - and more importantly derogatory and demeaning - replies, worse even than I had experienced on Reddit, which at this point is really saying something! I stopped replying, I think I deleted the original comment or edited to say that I would no longer be replying, nothing helped. My consent to the “dunking” process was irrelevant - never mind that I was not OP, never mind that I had not read the community statement prior to engaging bc it appeared as an isolated post in my All feed, I was now being used as a target to vomit their feefees (feelings) all over onto.

And then a week later I did the same in a lemmygrad.ml post. I almost left the Fediverse after that - there is zero reason to put up with such nonconsensual and unannounced shit voluntarily. However, I was not made aware bc I was relatively new to the Fediverse, and my prior instance (Kbin.Social) had preemptively defederated from them, so I had no idea what I was walking into. Fortunately v0.19.3 came out allowing user blocking of an entire instance, so I blocked them all, recently adding lemmy.ml to that list, and now I’m happy.

So go to those instances at your own risk. No, it’s nowhere close to mere differences in “political thinking”, it’s more like if you want a polite conversation using factual statements and logical reasoning vs. the polar opposite of that where if you don’t parrot the talking points precisely then you get ridiculed ruthlessly for not knowing their internal set of “alternative fact talking points”. i.e., I suppose it’s what passes for “political differences” these days, like Russia would like to commit genocide in Ukraine while the latter would like that to not happen - you know, a “political difference”.

If you are interested, here is a link to where I previously answered someone asking why people defederate from hexbear.net, including a link to read their very own words along with my commentary on that.:-)

I left Lemmy World in favor of my current account due to them defederating from instances. I like to be able to choose what I can and cannot interact with, and SDF doesn’t defederate with anyone.

Lemmy allows for individuals to block instances in the account settings anyway.

AFAIK, lemmy.world defederated from hexbear due to political differences.

Lemmy World announced the block about 10 months ago: https://lemmy.world/post/2498330

The larger instances usually setup a community just for announcements. For world it’s !lemmyworld@lemmy.world