I was hoping someone would have something about learning to give criticism. I was legit scared when the top posts are, "learning to take criticism is how you become a senior programmer."

Not that that is worthless, mind; but becoming aware of that in the process is what makes you senior. By definition of it being part of growth. With time, you will have been no both ends of more and more reviews. Hopefully you start to see how both sides of the conversation that is a pull request go.

And note that you can't "policy away" bad snarky comments. If someone is giving a ton of those, or is generally tone deaf, work with them. If it is someone you don't want to work with, pull in peers to help work through that. If you don't have a support network, start there above anything. Even if things seem to be going well, having peers to lean on is important for the times that it doesn't. Learning to be a good peer is equally vital, and is a part of what makes the reviews more relatable and part of a group project.