Does the controller go back to the supply after use?
Answer from this thread on BGG:
It only gets returned to the supply in solo. When not playing solo, the controller doesn't go back into the supply.
Pre-production Rulebook:

Whenever any player (including the player with the Controller) visits a destination with Scout on it, the player with the Controller may choose to gain a Sun Crystal or a Fast Travel token from the supply.


Solo Mode: Playing Against Scout
If you visit the same destination as Scout, you must spend a Sun Crystal or return the Controller to the supply.

Tabletopia Rulebook:

When any player visits a
destination with Scout on it, the player with the Controller may choose
to gain a Sun Crystal or Fast Travel pass from the supply.


Solo Mode
[...] if you wish to visit a destination with
Scout, you must spend a Sun Crystal or return the Controller
to the supply.