Almost any form of multiplayer seems to be unstable, and isn't very consistent. Realms and Servers alike (private and public) aren't at all reliable.

Going on a multiplayer platform of any type after 1.16.2 and playing just like on 1.16.1. No mods or plugins necessarily used. Performance and reliability of all multiplayer mediums for Java 1.16.1 seemed to work perfectly fine.

When actually trying to go onto a Realm or a server, one of 2 things happens. An immediate kick with an "java.io.IOException," or failure to render skins of other players, and blocks. Essentially creating a void full of Steve and Alex skins.

To recreate, simply login or join a server, or Realm running on 1.16.2. No mods or plugins used.