Teleportation to and from the Moon or Mars has no experience cost making travel a bit too easy. Perhaps require 6 levels to teleport to/from other planets.

All config options enabling experience use are enabled. I'm not aware of another option to specifically add experience costs to travel to other dimensions. Is there a place you have seen that is able to do this?

Looking at the code for Waystones, it doesn't take dimension changes into account when calculating if the destination waystone is within the "Short Travel is Free" distance and therefore qualifies as no cost.

The "Short Travel is Free" distance is determined by the "Blocks per XP Level" value. If the distance between the player and the destination is below the "Blocks per XP Level" value, it is considered short, even if they are in different dimensions.

In the near term, you could either turn off "Short Travel is Free" or set "Blocks per XP Level" to a smaller number so that it is less likely that player and destination waystone will be within the "Short Travel is Free" distance when they are in different dimensions. The XP cost is capped by "Maximum XP Cost" so this is not really impactful.

I opened an issue with Waystones to take dimension changes into account for the "Short Travel is Free" calculation. TwelveIterationMods/Waystones#191