The only effect of a Code of Conduct I have ever personally witnessed was that people were being bullied for greeting others. The greeting they used was "hey guys", and instead of recognizing that language is fluid and different to different people they tried to impose their linguistic views on others. The people who encouraged this behavior were people on the Code of Conduct committee and at the top of the project's…
I’ve been working on open source projects for about a decade now, including years of professional work, and I have never seen or heard someone chastised for using “guys” informally. This includes in communities with established, formal codes of conduct. It strikes me as something that most people wouldn’t even notice, unless the speaker was intentionally using it in a way that implies gender.