For me, it was mostly privacy and being a time suck. I got very little value out of it for how much time I spent on the platform, and them being openly hostile to my privacy made it that much worse. So it was very much a selfish decision, not a "moral obligation" or whatever.

Morality would only get into it for me if they were complicit in protecting child abusers or something. But giving people what they say they want isn't immoral, but it's borderline unethical if they know what people claim they want is harmful. But honestly, I don't think any tech platform should be deciding what is good or bad for people, they should merely provide a service. I see Facebook as essentially just providing a service, and they do a really good job at that, but whether that service has value is another discussion (I don't think it does, at least not positive value).

So I don't think Facebook is immoral, and whether they're unethical really comes down to what obligations you think a tech platform has. I think people shouldn't leave Facebook for either reason, they should leave because they'll likely have better mental health, lower risk of being radicalized, and more time to pursue things they find value in. Take all the energy you spend on Facebook and make your corner of the world just a little bit bitter.