Question Ecpm from Admob Mediation Lower than Unity.

I'm very sorry for not being a good English speaker.
So I will try to make it easy to understand. If there is any problem ask.
Please comment below. Thank you.

[My problem #1]
My app plays Unity ads through Admob's mediation system.
This is the Ecpm I get.

Can be seen significantly increased after using unity's SDK.
Is there any way to solve this problem?
I still want to use Admob Mediation because it's more granular data connection.

[My problem #2]
I only get close to 50% March Rate. How to get more?


Thanks for your help