The problem is your avatars having invalid items - the current solution is to randomize it until you can join the servers. A fix is in the works and will be deployed as soon as we can.
Sea Otter and White Tiger are the names of official servers that currently serve as servers for playtests and have their own build beta branches on Steam, next to Coast Redwood, Giant Panda and Darwin's Fox. They are named after endangered species, with the special name for White Tiger signalling it working a bit different.
devtrackers.gg