AdMob mediation + house ads

Can someone please explain how does the combination of AdMob mediation + house ads work.

How often are the house ads displayed ?

I can understand if we put the lowest eCPM for house ads, it should be displayed if there is no other ads.

But if we put the highest eCPM for house ads, what does that mean ?


its broken doesn’t work more info here


Are they aware of the problem ?