Now people can find your alts via
GuildOx.
If you don't want your alts to be known then it can be disabled by going into the game, selecting Interface/Display and then checking the "Display Only Character Achievements to Others".
Note that you must actively log into your alts in the game for this detection to work - account-wide achievements are refreshed when a character logs in and out of the game and we require the achievement points to match across characters for the alt detection to function.