I had the same thing happen. I didn't realize why until I started getting a "some apps or processes are overloading the system (cpu) and need to be closed" and indicated that it was the Google play services app. So I did a web search and the basic solution was to uninstall the google play service app, then I cleared the cache on my phone (in that order). After that, the ads disappeared. The ads appear to be part of the google play services app. If you have programs that need the google play services app, it seems as if we are stuck with the ads. They do use up a lot of data and wears down the phone battery faster. I hope this helps answer your question.
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