We have from time to time people making a new post rather than replying to the post they were reading. It can be a lip of the thumb on a phone or just the placement of the blue buttons on the site.
It is much better to reply to the original post as it makes sense first of all and if it was on its own it will not. But also if you are thanking or replying to something in that post then the people on the post will be notified where they will not on a brand new unconnected post.
So we will tend to lock the new orphan post and put a note on it and then possibly remove it later.
This video may help explain the difference between replying and writing a new post. Hope it helps. Has audio but we may add text at some point.
screenrec.com/share/d92WUVKocJ - video on how to reply rather than write new posts