I don't seem to find any related discussion on this yet. Google recently appears to have updated their policy to prohibit users from rendering ads separately with an iFrame
"AdSense code may not be altered, nor may the standard behavior, targeting or delivery of ads be manipulated in any way that is not explicitly permitted by Google. This includes but is not limited to the following: clicking Google ads may not result in a
new browser window being launched, nor may Google ads be placed in an IFRAME."
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labnol.org...]