Ask HN: How do you handle toxic coworkers?

I recently started a new job (web developer). One of the other coworkers is passive-aggressive and judgmental. Someone broke production today and he left several comments in Slack that seem intended to make this person feel bad. His comments are usually just tame enough not to be obviously abusive but hurt nonetheless. He frequently leaves the thumbs-down emoji as a comment on a PR (with no explanation or suggested improvement) and tells people that decisions they've made "don't make sense" or are "weird". Leadership doesn't seem bothered by it and even invite him to "do his worst" when leaving comments on a PR. I've only been here a few months and I'm completely sick of it. I come home wiped out whenever I have a bad interaction with this person, which is several times a week. I would like to quit but I don't have another job opportunity. How would you deal with this person? Just ignore them? Call them out when they are being passive aggressive? I've tried to feel out my manager about the situation and he seems mildly unconcerned. It feels like there's a lot of potential for me to be labeled "too sensitive" or "not a good fit".