I'm going to relate my personal experience. I'm not saying that these events will happen to everyone, but they definitely happened to me.
Approximately one week ago, I posted on Next Door in response to someone else's posting. In my response, I quoted some health statistics I found on the web. I included my source, as I wanted to be clear about where I had gotten my information.
My post was taken down subsequently. No explanation, no advance warning, nothing.
I then posted a polite request asking the admins to please explain when they remove someone's post. Many users agreed with me.
Subsequently, my second post (requesting an explanation) was removed. Again, no explanation, no warning, not even a courteous reminder.
Use Next Door at your own risk.