What is palace "ghosting" (interference), and when does it happen?

Faint leftover images from previous content haunting a palace you've reused too soon — old ghosts mixing with new items.

If you store this week's shopping list in your home palace, then next week store a new list in the same palace before the first faded, you may "arrive" at the sofa and see both the old moon and the new rake. The fix: either let old content decay first before reusing, keep a rotation of several palaces, or reserve some palaces for permanent information you never overwrite.