No, it is not normal, at all. From what I gathered reading hundreds of thousands of reddit and lemmy posts, it's a young person thing.

We GenX kids had zero problems discussing our deepest fears among each other. Can't think of a single instance of anyone worrying about how to act in simple public situations.

I'm probably biased as old reddit and lemmy aren't representative of society in whole. I have several friends I've known since their late teens, early 20s now, and none of them talk about social anxiety.