I don’t know why you see ads on your site, but I guarantee you that we didn’t put them there. Maybe there is a browser extension or website proxy that is injecting the ads into the page?
This gives me a very strong feeling that there is some network web proxy in between you and our servers that is injecting the ads. When you use HTTPS, the connection between you and our server is encrypted, which means it’s impossible to inject additional content into the page. But on an insecure connection, adding additional content to the page is fair game because there is nothing to prevent that from happening.
Both browser extensions or anything on the server would be able to inject ads regardless of whether HTTPS is used or not, so it must be somewhere else.