Haha this just happened to me on my very first ever post to Lemmy and I was about to ditch this app. Not really. But I did copy my somewhat long post just in case. And I'm glad I did because I had to refresh and paste again and submit. However, within that issue, I found a weird bug. I had clicked on another post b4 going back to the thread that I wanted to re submit my comment. I checked out my profile to see my first comment and for some reason, my comment got posted on both threads, the related thread and the non-related thread. Devs might want to look into that one.