Hi, It does sound like pop-ups, but if you can send us in a screenshot of the page, that may help, and I've asked tech support what they think it could be.
You're accessing HC via Chrome on your smartphone?
Next benefit would be to capture the URL of the advert you're sent to, in case our ad agency can identify is as it may be a rerouting of a 'real' ad that has been inserted maliciously.
info@ is the email to reach support if you have images to add, as I don't think they can be inserted from the support tab.
Thanks.
