Setup a scene region and add the Difficult Terrain behavior. Then take a token, change it's Movement Action to Teleport (Blink) and start dragging it into the region. As soon as you cross into the region, it becomes difficult terrain and the movement distance doubles. There should be an exception for Difficult Terrain if you're teleporting.

I also noticed it with the Jump movement action. That one might be a bit more situational, like you can avoid difficult terrain if jumping through "Rubble or Rocks" but not "Sticking Webs."