Wrong place to post this but anyway you're either shoutbox banned or you need to rejoin Aquatic Moon box try this here https://prnt.sc/BNpH0rjoWVeV if you're not banned "Join Room"
Hello mate, i don't see this has gotten a solution yet.
I can say you either clicked "leave" by mistake or you have been shoutbox banned.
I believe if you're not banned you should be able to rejoin the shoutbox.