Hi there,
Nice to meet you.
We have noticed that, in a few cases, AdMob/Vungle mediation has this issue (low fill) at a moment.
We are investigating this issue as first priority.
If you can send a message to [email protected] with your AppID, that'd be super helpful.
I will update this thread as soon as we locate the problem.
Sorry for the inconvenience,
-aki