There's not much I would post on Facebook that would cause me heartburn if a potential employer were to see it. (And most of my Facebook friends would be profoundly uninterested in most tech topics I would post on.)
But, yeah, I keep my LinkedIn--to the degree I use it at all--very anodyne except to the degree you have relatively extreme opinions on specific tech topics.
I don't have a facebook, but I don't think I post anything that's likely to get me fired to any social media. However, there's sort of a difference between "not being fired" and "being hired".
My political opinions are pretty normal (basically typical American lefty), and if my employer were to find a blog post I wrote about universal healthcare or something it's doubtful that they'd fire me. That's a little different than me plastering "BIDEN 2024!!!" all over my resume, and that's why I utterly hate LinkedIn.
But, yeah, I keep my LinkedIn--to the degree I use it at all--very anodyne except to the degree you have relatively extreme opinions on specific tech topics.