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.
It’s problematic because often you’ll get an error that says it failed to post the comment. In which case it’s fair to try again, but it actually posted anyways.