On my current job, one of guidelines says that if something is not important/very personal preference, you can prefix the comment with words "nit:" that means "nitpicking", and author can either change if it sees fit, or just acknowledge comment and go on.
Other thing is not to be shy to tell that suggested change is outside of the scope of this changeset, and will/may/might be addressed later.
Sometimes, if there is a lot of back and forth, it is easier to set pair programming session and address everything in one session.
Last option is raise that with management, if you can justify your opinion that such loop doesn't bring the value for the time spent on it, especially if you know that there are other engineers in the team who feel the same.