When I receive a PR that has actual problems, I usually make a branch from the code in question, and submit a PR to that branch with tests highlighting the prob

When I receive a PR that has actual problems, I usually make a branch from the code in question, and submit a PR to that branch with tests highlighting the problem, or the beginnings of a refactor that I'm asking for. I often don't have time to fully flesh out the problems, but helping to write the software with the requestor makes for much faster and effective feedback than plain text comments.