The tone of code reviews can greatly influence morale within teams. Reviews with a harsh tone contribute to a feeling of a hostile environment with their microaggressions. Opinionated language can turn people defensive, sparking heated discussions. At the same time, a professional and positive tone can contribute to a more inclusive environment. People in these environments are open to constructive feedback and code reviews can instead trigger healthy and lively discussions.
Good code reviews ask open-ended questions instead of making strong or opinionated statements. They offer alternatives and possible workarounds that might work better for the situation without insisting those solutions are the best or only way to proceed. These reviews assume the reviewer might be missing something and ask for clarification instead of correction.
Better code reviews are also empathetic. They know that the person writing the code spent a lot of time and effort on this change. These code reviews are kind and unassuming. They applaud nice solutions and are all-round positive.