I get this exact feeling, sometimes to the point where I'll block an entire community. I work a lot with people, and I speak regularly in front of large groups, but I've never experienced the kind of aggressive comments in real life that I do online. It gets exhausting. And I know that I can block people, but it's also hard to distinguish between people who are just having a bad day vs. someone who's an exhausting troll or debatebro. I usually can't tell the difference until after the struggle session, when I'm exhausted from arguing against ... usually against points I didn't even make lol

Edit: Just saw someone on a .world community who is repeatedly misgendering a trans person. I totally think "inbox fright" is valid, and the people who think it can just be ignored are not the ones who are in marginalized groups who are frequently targeted by hate. Even a good ally will get inbox fright, because these users will turn on you too, if you call them out for their bigotry.