There are code reviewers who know what they are doing, and if they say something needs to be changed, then it needs to be changed, and when they say something needs to be tested, then it needs to be tested.

There are code reviewers you are just ***holes on a power trip who need to justify their own existence by creating useless work for others.

Which one is which is for you to decide, and how to handle the second kind is more a question for workplace.stackexchange.

If you use scrum, then the question is whether your work does what it is supposed to do (apparently it does), and you can put handling the extremely rare and maybe impossible case on the backlog, where it will be prioritised, and if it goes into a sprint, then your reviewer can feel free to pick it up and do the 13 hours work. If you do job X and because you do job X you realise job Y also needs doing, then job Y doesn't become part of job X, it is its own independent job.

There are code reviewers who know what they are doing, and if they say something needs to be changed, then it needs to be changed, and when they say something needs to be tested, then it needs to be tested.

There are code reviewers who need to justify their own existence by creating useless work for others.

Which one is which is for you to decide, and how to handle the second kind is more a question for workplace.stackexchange.

If you use scrum, then the question is whether your work does what it is supposed to do (apparently it does), and you can put handling the extremely rare and maybe impossible case on the backlog, where it will be prioritised, and if it goes into a sprint, then your reviewer can feel free to pick it up and do the 13 hours work. If you do job X and because you do job X you realise job Y also needs doing, then job Y doesn't become part of job X, it is its own independent job.