I’d try to respond to PR comments/ talk or slack directly with the person and ask them to elaborate whenever they leave these negative ambiguous comments. You can even preface it with some humility - “I’m struggling to understand your point, could you restate this in another way for me?” You can keep going down this, and if they are just being catty, disrespectful, etc, you can potentially ask other developers to way in with their opinions, to help come to some consensus.
As for the mocking regarding production going down, I’d counter if possible in the thread acknowledging that even the most experienced developers write bugs, and this speaks to a system problem, not an individual developers fault. I’d try to remove blame from the individual.
Finally, I’d recommend trying if at all possible to get a little distance from the situation, whatever the comment is, etc that is bothering you. By that I mean trying to not let it get under your skin by focusing on your task at hand despite the negativity (be extra positive instead), maintaining identity outside of work and allowing yourself some self confidence in your skills and yourself.
Remember: a) this person might be or act like an asshole (maybe they are just really insecure? Who knows? Doesn’t matter?) b) management is complicit c) you maybe able to change behavior but may not d) you may not be able to control your understandable and appropriate emotional response to the person now, but if you practice mindfulness (pausing and keeping perspective), you maybe able to mediate your response and feel better about the situation.
Good luck! I’m feeling for ya!