When a WorldGuard region has the correct command to deny teleportation into it in the blocked-cmds flag, players in the same server who do not have the bypass permission aren't allowed to teleport and are told that their teleport was denied, as expected. The same doesn't apply for teleporting between servers however. The player is told that they aren't allowed to teleport, but are teleported to the restricted location. This also appears to overwrite their previous location (the one used by /back) to the restricted one.
When a WorldGuard region has the correct command to deny teleportation into it in the blocked-cmds flag, players in the same server who do not have the bypass permission aren't allowed to teleport and are told that their teleport was denied, as expected. The same doesn't apply for teleporting between servers however. The player is told that they aren't allowed to teleport, but are teleported to the restricted location. This also appears to overwrite their previous location (the one used by /back) to the restricted one.