How to proceed when your app is going to be banned from the Play Store...

I'm the developer of a Podcast app on the Play Store named Podcast Addict.
I'm currently having 200K users and almost 400K downloads. Users seems to enjoy the app, which has now 18K reviews ( more than the leader app BeyondPod ).
The current rating is 4.5/5.
The app is ad supported with no feature limitation, and there's a paying version that removes the ad banner.

Everything was fine until I received the following mail from Google:

Subject: 7-Day Notification of Google Play Developer Term Violation

This is a notification that your application, Podcast Addict, with package ID XXXXXXXXXX, is currently in violation of our developer terms.
REASON FOR WARNING: Violation of the Ad Policy:
After a regular review, we have determined that your app causes users to inadvertently click-through ads to access the app. This violates the Ad Policy. Please refer to the ad walls policy help article for more information.
Your application will be removed if you do not bring it into compliance within 7 days of the issuance of this notification. If you have additional applications in your catalog, please also review them for compliance. Note that any remaining applications found to be in violation will be removed from the Google Play Store.
Please also consult the Policy and Best Practices and the Developer Distribution Agreement as you bring your applications into compliance. You can also review this Google Play Help Center article for more information on this warning.
All violations are tracked. Serious or repeated violations of any nature will result in the termination of your developer account, and investigation and possible termination of related Google accounts.
The Google Play Team

I'm only using Google Admob library and Google Admob network.
I'm not sure what the real issue is, and therefore I'm not sure how to fix it.
Current Admob library hides the ad banner and only shows it once the ad has been downloaded. That might be the reason for the mail, but this is the banner behaviour, not my implementation. I just find out that using Admob through Google Play Service reserves a space to display the ad banner, so I just switched to this lib and published the new version.
Maybe there's no more issue with my app, but how can I be sure ?

If you have some information on this topic feel free to share.