Many services have their links "banned" or "tagged" in Google Ads. I guess clickbank is no exeption. I used networks like OGAds or CPAGrip and all my Ads were rejected after 1-3 days because of the "malicious software". Big services rarely update their domains/links/trackings, people abuse them on Google Ads, so they reject them - even if the landing page is clean and virus free. There is nothing you can do about it, maybe cloaking would work, but I have no idea about cloaking because never used it.