Hello, it's not a bug, as explained there: http://app.ryzom.com/app_forum/index.php?page=topic/view/27050/2# 2
The vest and pants/skirts are not unequipped not to force to have a naked character.
- Q: What will happen if, after returning to Free to play mode, I connect a character still equipped with equipment requiring Premium mode?
- A: The equipments (excluding vests and pants/skirts) that are of higher quality than what Free to play mode allows and will fall automatically in your bag.
The vest and pants/skirts are not unequipped not to force to have a naked character.