Lavabird Ltd.'s Barcode Scanner, available for years in Google's app repository is the culprit. Adverts suddenly started unexpectedly appearing on Android devises after the update. Malwarebytes discovered the malicious code buried deep in the app update.
If you have that app on your device remove it now.
With one update, this malicious Android app hijacked millions of devices | ZDNet
If you have that app on your device remove it now.
With one update, this malicious Android app hijacked millions of devices | ZDNet