In dust's kit, it states that "when the opponent purifies a Debuff, Dust deals a burst of physical damage. This ability has been working until recently where the debuff gets purified but the opponent suffers no burst of physical damage.

Here is a video Showcasing the issue:
https://drive.google.com/file/d/1E_BVE7LgKRfJJE4KVQCAGsY61pAfS75H/view?usp=sharing