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.
You should also know you can join smaller instances to help alleviate this problem. You’ll still see most of the same content, especially if the instance has active users. Don’t be too shy to sign up on some random instance, worse case scenario you just don’t get approved.