Infernalist slowed in Trials of Sekhemas from Infernal Flame damage with Worn Sandals Debuff

Worn Sandals in Sekhemas gives a 30% movespeed debuff if you've been hit by an enemy recently. However, Infernalist Infernal Flame self damage will also trigger the slow. For my character, I have a 63.2% movespeed modifier on my stat sheet. But when taking damage from Infernal Flame, it drops to 14.2% even though no enemy hit me.