The bug is that almost(?) any source of Restoration will reset your current Restoration timer to the base duration for the source that was applied to you, regardless of your current Restoration timer. If you have 12 seconds of Restoration and walk through a Sunspot, you'll get chopped down to 5 seconds. If you have 12 seconds and touch a Firesprite with Ember of Mercy equipped, you'll get chopped down to 2 seconds. This same bug applies to sources of Restoration x2 as well. This bug is extremely damaging to Solar subclasses trying to enhance their survivability, particularly with Ember of Empyrean, as it forces you to actively avoid huge parts of your Solar subclass's build and abilities. It has existed since Solar 3.0's introduction in Season of the Haunted. I would expect the Restoration timer behaviour with ember of Empyrean to work pretty similarly to how Echo of Starvation/Feed the Void works with Devour. At the very least, shorter duration sources should not be overwriting longer durations of Restoration.