On my team, the PR author is ultimately responsible for their work. All review comments are considered suggestions. The Approve button is used only to indicate completion of the review. If a reviewer has a problem with the merged work, they can open a new case describing the problem.

We train all developers to have sufficient competency to work on any part of the code. If some code is too complex for a developer to understand, it is simplified. Documentation is prioritized and included as part of the work effort.

We have worked together this way for about 7 years, with high developer satisfaction and low turnover. The quality of the product has steadily improved during that time.