Jotaz boss in coliseum is ramping speed

As the Jotaz boss takes damage it is ramping it's speed. I did several extra battles to confirm, and the boss is gaining speed to the point that it begins being able to take multiple turns in between my units turns. This is not being caused by buffs being gained / lost, this is just pure speed. At no point did I take 10 consecutive turns to trigger the unique.

Either the tooltip needs to be changed to indicate that it increases both its speed AND offense as you gain points, or it should not be gaining speed.