With the sluggishness of the site these last few days you can sometimes get slowness or infinitely loading icon when hitting submit. If you aren’t sure if your post submitted, refresh the original page in a different tab before hitting submit again to see if it went through. I see double and triple posts in almost every comment section.
The problem is a UI thing too. In wefwef for example half the time you go to post something and it says ‘error posting’, your comment actually did post. But sometimes it doesn’t.
I typically go until I see success and then delete any duplicates I left on accident.