I don't like this approach either as maintenance gets complex over time. Changing routes in my React-router project is one file, one commit that's easy to verify, try changing a dozen routes with Next and you end up with a dozen of files moved around, with folder structure possibly impacted as well, I see this as an anti-pattern.
That's true, the pull request diff viewer does not make viewing file renaming very clear and there could be conflicts.
On the other hand, what I see in practice is adding or removing context providers and layout components in the react router file, it becomes huge, and all the diffs change all of the lines with new indentation.
