Can someone explain me what actually is going on about the politics drama and public perception of lemmy?

No shit it's not private. This is the digital equivalent of shouting on a soapbox in public and then getting pissed if someone records or remembers it.

The developers, I'm told, have taken some controversial positions such as questioning whether North Korea is much worse than South Korea or whether China is really conducting a genocidal campaign against Uyghurs. Some people seem to be concerned about that in the following ways:

1. They worry that by using Lemmy they're endorsing the developers' political views.
2. They worry that the developers will develop the software in ways that bake their politics into it somehow, or that are influenced by their politics.

I'm not convinced by either. To the first point, Lemmy is a piece of software for running communities on federated instances (sites). Each community has its own character and each instance does too. By design it's not monolithic but distributed and diverse. The developers have never given any indication that they want the software used only to discuss things from their point of view; in fact they've indicated that they want it to be able to host a diversity of views.

To the second point, the code is open source and anything politically loaded would be out there for anyone to notice. It would get spotted, and other developers would be able to fork the code and remove it. Instances could then run the forked version. Since ActivityPub, the software that handles the federation, is not part of Lemmy, they couldn't politically tilt that anyway.

Mostly I think what we're seeing is people with an interest in the status quo (communities hosted and controlled by profit-making companies) using vague and unspecific allegations ("the developers are tankies!") to spread fear, uncertainty and doubt about an uncontrollable democratic alternative that threatens these corporations or those who are given power by them.

First off, there is nothing stopping anyone from making a bot that scrapes off raddle and posts it elsewhere. When you post publicly, its just that, public. In fact, there are likely already bots doing it.

Second, not using Lemmy because of the developers is certainly their choice, but its also like saying you refuse to use email because people you don't like use it. Just be selective of the instance you join. And if you are that worried about something sneaky, the source code is even open source.

It all comes back to the definition of "privacy" and whether it is reasonable to expect that information, once posted to a publicly accessible forum, can be considered "private".

Is it even reasonable to expect information that isn't transmitted via some method which features end-to-end encryption to remain private?

Maybe I'm just old-school, but I've lived my life by the philosophy: "if it is private, don't post it" Frankly, this should be the first thing we teach kids about the internet, IMHO.

A decentralized system is much more like email than people may be used to. I can ask someone to delete an email and they might even say they did, but it doesn’t mean it’s true.

If I delete content on Reddit it disappears from Reddit, because there’s only one and they control it. That doesn’t necessarily mean they deleted it either, but at least it doesn’t show up on the page anymore. That also ignores that Reddit has been scraped and archived for years and years by third parties, so there is a good possibility it still exists there too. (This scraping could eventually watch lemmy too).

A public forum is a public venue, best to assume the lack of privacy.

Edit: as for the political stuff brought up in the comments, I have said before that I think people need to think about the admins of an instance when they choose to host a community in that instance, that does not mean the project is an issue. The developers have been very supportive of people’s rights to think differently than them.