Merci bugged?

As far as I got mercies should have had around 1600 damage in total (Damage 79 and Damage ticks 20), but when I tested the damage in sandbox, it appears that mercy deals 600 damage to all the units. So I have not got how they should work. Is "damage ticks" the number of ticks and every tick is dealing 79 dmg or is it so that every tick deals 20 damage? If second, then it is still delivering not wrong amount of damage. I assume that they are bugged, aren't they?

600 was always the intended amount of damage. Why it's 600 and not 79*20 is... complicated, but there's a thread in the Discord Balance Discussion about it.