A few months back, I was using a github repo and found that it has some bugs. It took me one whole night to fix it. I submitted a pull request with the fix. Now, instead of just merging it, the owner of the repo added a code review asking me to fix some conventions (and the conventions he suggested did not conform to the official style guide of the language + he could fix them faster than writing the code review) and asked me to do additional things that had nothing to do with the bug fix.

I guess this is an example of a toxic code review or what I call "code review for the sake of code review". It turned me off so much that I haven't responded to it yet.