After removing the sender UUID, the client will still attempt to parse the username when using the standard chat format (<sender> message). The config option invisibleNameCharacter exists to combat this.
It'll add an extremely small character in front of the player's username, causing the client parsing to not find any players. This may have the side effect of breaking bots and mods attempting to find the author of a message by parsing chat.
This option will do nothing if you're not using the default chat format.​