A study by OpenWeb (2020) on their own platform* found that about half of users either revise their comment or decide not to post it when prompted that their comment may be inflammatory.
"The overall positive outcome of this experiment reinforces our belief that quality spaces and civility cues drive a better, healthier conversation experience." write the study's authors. "A gentle nudge can steer the conversation in the right direction and provide an opportunity for users with good intentions to participate. The feature provides more transparency and education throughout the user engagement journey boosting loyalty and overall community health."
*Important Note: this was a study of their own platform, which they sell as a service.