That is a Cloudflare ban. If it happens again, the first thing to do is just try switching your browser. E.g. Download Brave, or Firefox or Chrome, or whatever, just use a different one. It can block you by browser fingerprint. If that does not work, it has blacklisted your IP address, and you need to use a VPN or a Tor browser to defeat the blocking. They have an algorithm for detecting unusual network activity, and it can end up blocking people for no reason.

This was not the result of an admin, or it wouldve let you log in, just not let you post. Hope that helps you in the future.