It’s worth reaching out to Google Support. They’d be able to check / help crawl the URL you’re using for the ads and which page it’s found specifically. You will be asked to remove that content or link from your website backend.
In my experience, it happened because turned out my client was using third party blog/article generator to publish article (cant remember it correctly) which caused Google Ads’ automatic crawl to detect that link as malicious software / circumventing systems.