I have Google ads on my site, but only for non-members. I check to see if the person viewing the page is a member; if they are, no ads.
So, I started seeing ads when I was logged into a test account. The account had a membership, so I should not have seen any ads.
I went through all the code, checking to make sure the “if @member” test was there. All was right, but still ads showing up.
After MUCH digging around, I discovered the cause: There is a setting in the AdSense control panel, under Optimization, called Experiments. If that is set to on, Google can serve whatever ads it wants on your site, without any AdSense code in your HTML.
I don’t remember turning that on, but perhaps I did. At any rate, I turned Auto Optimize off, and the problem went away.
FYI.