The glow of teleportation often has to do with the transfer plane and the destination used by the teleportation spell.
When the destination of the teleportation spell is another corner within the same plane, the teleportation glow is white.
If it points to another plane, it displays the color of the destination. For example, pointing towards the Grey Corner sub-plane would be grey; pointing towards the Thunder Sea plane would be a deep blue color of seawater.
If pointing towards the Mystic Mage Headquarters, the teleportation beam would become purple-blue.
Yes, the Mystic Mage Headquarters is established in a separate sub-plane.
Its name is known as the [Mysterious Blue Forest], also referred to as the [Mystic Mage Forest].
The spells taught here are not like the public teachings of the Tower Scholars in the Holy Place educational district.
The Tower Scholars can't shed their scholarly nature, their spells are more focused on versatility and high precision.