If I’m doing the review, I try to find at least one or two items to call out as great ideas/moves. Even if it’s as simple as refactoring a minor pain point.
If I’m being reviewed I always make sure to thank/compliment comments that either suggest something I genuinely didn’t consider or catch a dumb move that isn’t wrong but would be a minor pain point in the future.
As you note, code reviews can be largely “negative feedback” systems, and I find encouraging even a small amount of positivity in the process keeps it from becoming soul sucking
So actually putting positive comments in the code review isn’t really much appreciated.
I gained this habit and now for me, a comment is a suggestion of improvement, I deliver praise out-of-band.
It's a horrible practice with adverse incentives, and one of the reasons I'm glad I no longer work there
(and easily gameable, anyways - people would just DM each other patches they were unsure of, before submitting an actual CR)
If you listen to interviees with great writers, musicians, painters or actors you will often find it surprising when they tell you which other arrists they like. That is because the people making the stuff often have a much more open mind about what constitutes interesting and/or good writing, music, paintings or acting.
To me as an practitioner it feels at time that these "enthusiastic consumer critics" are incredibly bitter about not being able to live from the art they love like the ones they critique, so they carve out their niche and give themselves self-worth by playing a strong role in the field they love.
With good critics this love is the predominant message, with bad critics it is the bitterness.
"Why did you not handle $situation" -> "how does this code handle $situation?"
"You shouldn't do $thing" -> "$thing has sharp edges, see $link-to-more-info. The general approach used in the code base is to $alternative."