Comment by jampa

I wrote about this recently. You need to prompt better if you don't want AI to flatten your original tone into corporate speak:

https://jampauchoa.substack.com/p/writing-with-ai-without-th...

TL;DR: Ask for a line edit, "Line edit this Slack message / HN comment." It goes beyond fixing grammar (because it improves flow) without killing your meaning or adding AI-isms.