When writing an inline comment, there’s a button to make a suggestion. It inserts a markdown code fence with the existing code on the line(s), which you can edi

When writing an inline comment, there’s a button to make a suggestion. It inserts a markdown code fence with the existing code on the line(s), which you can edit. When you submit the comment, it shows up with diff highlighting and can be applied by the author with one click. Essentially the same thing exists in both GitHub and GitLab