"Soul Raiders" event bonus is not multiplying

When we use an all undead team*, we get +20 souls bonus during Explore.

But that bonus is flat.

Meaning I can use a standard team and get (for example) 200 Souls
or
I can use an Undead team and get a total of 200 + 20 = 220 Souls

Is this working as intended, or should that 20 souls bonus be multiplying by our Explore/PvE bonuses?

  • Or whatever it is next week.