I came here to post the exact same thing. I find using "we" is a good workaround. And it's not just a euphemistic way of saying "you" — as a code reviewer, I know I'm also responsible for catching bugs or performance regressions, and by saying "we" I feel I'm expressing that shared responsibility.
You can also use "I". Trying to avoid pronouns can make it sound like a high school lab report with excessive passive voice (e.g. "The baking soda was mixed with the vinegar" vs. "I mixed the baking soda with the vinegar").
In this example, I might say "This seems very complicated to me. Would a simpler model work?". If I had something simpler in mind specifically I would suggest it.
