AdMob (Google-Mobile-Ads-SDK) iOS repeating message in log: "ProcessThrottler::Activity::invalidate: Ending foreground activity..."

When I run an iOS app using the AdMob plugin on a device, the console log keep repeating with high frequency.

ProcessThrottler::Activity::invalidate: Ending foreground activity / 'WebPageProxy::runJavaScriptInFrameInScriptWorld'     ProcessThrottler::Activity::Activity: Starting foreground activity / 'WebPageProxy::runJavaScriptInFrameInScriptWorld'     ProcessThrottler::Activity::invalidate: Ending foreground activity / 'WebPageProxy::runJavaScriptInFrameInScriptWorld'     ProcessThrottler::Activity::Activity: Starting foreground activity / 'WebPageProxy::runJavaScriptInFrameInScriptWorld'     ProcessThrottler::Activity::Activity: Starting foreground activity / 'WebPageProxy::runJavaScriptInFrameInScriptWorld'     ProcessThrottler::Activity::invalidate: Ending foreground activity / 'WebPageProxy::runJavaScriptInFrameInScriptWorld'     .... 

The Google-Mobile-Ads-SDK updated to latest version 8.12.0. If I disable GADAdLoader and GADBannerView, the repeating log will be disappeared.