If you obtain the absorption effect before to wear on the Wilted Ideals Necklace, your health will only be reduced in a half of an absorption heart.

This seems like a visual bug because the moment you lose any of the red hearts, the life refreshes.

Ye, don't really know how to fix that for now. Fun fact it's why it deals damage when you equip/unequip it, as a workaround to heart red hearts to update the visuals.