Jeff Atwood has a great article The 10 Commandments of Software Engineering (something like that) and one of the first ones is "you are not your code". There's no trick to this. Sometimes you write bad code. Even if you're a bitwizard demigod who can explain the route of an electron through your web3 Blockchain distributed app or whatever it is you do, you can still write bad code (and will). Nobody writes perfect code all of the time. Nobody writes beautiful mind algorithms all day with ease. It just doesn't happen.
Letting go of the ego a bit is something you have to find within yourself.
After that, it's easy. If the criticism is about the code, either accept it or be analytical with a thoughtful "defense" of the code. It leads to good technical conversation and the code benefits from it, and either one or both of you will learn something. Learning things tends to go away the more senior you get so the opportunity becomes exciting at some point.
If it's about you personally, then it's no longer constructive criticism and thus a civil response about keeping things on topic usually suffices.
I think of this in two ways. First, in a team, we're all collaborating on the project. Different people have different ideas and different experience, and debating can make for better results. In my last job, there was one particular person I disagreed with all the time (down to hops vs malt) but for that reason was a great person to collaborate with.
Second, there's code review. My last place was very much into its style guides and best practices at the individual PR level (but remarkably bad at higher levels; the prevailing large-scale design rule being ‘ship the org chart’). I think of that sort of code review comment much like a compiler or analyzer message: sometimes it's right, and caught a mistake. Sometimes it's a false positive, and you just have to change something to make the tool shut up.
(Third, I wouldn't be able to recognize an actual personal attack unless it were extremely blatant.)
Letting go of the ego a bit is something you have to find within yourself.
After that, it's easy. If the criticism is about the code, either accept it or be analytical with a thoughtful "defense" of the code. It leads to good technical conversation and the code benefits from it, and either one or both of you will learn something. Learning things tends to go away the more senior you get so the opportunity becomes exciting at some point.
If it's about you personally, then it's no longer constructive criticism and thus a civil response about keeping things on topic usually suffices.