Write a clear guideline, and ask team to follow it.
During the code review, you only ask to stick to guidelines (that everyone agreed on). This way programmers won't feel like your subjective opinion is affecting their work.
Its more than guidelines. Frankly the guidelines are arbitrary, and people's ability to find flaws and apply them just as arbitrary. What seems to happen quite frequently is that the guidelines just end up being used as expedient ways to say "I'm busy, go away" or "I don't like your patch, but can't find anything wrong with it" or any number of other non productive things. Reformatting code by hand is tedious, and every second typing "add a space here" in the code review subtracts from a second of understanding and analyzing the functionality of the code.
Which is why if you have coding guidelines they should be enforced by automated tools. Either the code passes the tool or it doesn't, no on is allowed to nitpick brace placement, spacing, or whatever. Use something like clang-format or whatnot and stick to it.
This can be done without it being a burdensome process or weaponized against an individual. Developing a team agreement with the team can be a powerful tool. It's important the team itself is the author, that everyone either agrees with a proposal or will go along with the rest of the team (if they won't, then its on them to form a counter-proposal), and that when the environment changes the team can revise it.
I think part of the issue is that when we, innocent readers on Hacker News, read something like this, we only know part of the story.
So we can't tell which party is the problem, and what the issue is and we end up second guessing the person asking the question.
The advice invariably tends towards finding an objective standard so that the person asking the question can check that they aren't the problem person.
Which is why if you have coding guidelines they should be enforced by automated tools. Either the code passes the tool or it doesn't, no on is allowed to nitpick brace placement, spacing, or whatever. Use something like clang-format or whatnot and stick to it.