Ads can't promote this content.
Advertisers that violate our policies may have permanent restrictions placed on their ability to advertise on Facebook.
Whenever you receive this pop-up message in your Facebook Ad Manager, it means doesn't not comply to Facebook Ad Policies. If you ignore the warning and proceed to publish your ad, either your ad will be rejected, or your ad account will get disabled right away.
I have pinpointed mainly 2 scenarios that lead to the above warning, as well as how to fix each of them below:
1. Your Ad Contains Restricted Elements
Facebook AI will scan your ad and scrap your website for flaggable keywords such as foul language, symbols, drugs, weight loss, n*dity or other sensitive elements.
The scope includes your ad caption, headlines, images, videos and landing page. Since your ad is not published yet, it will not trigger Facebook to restrict your ad account (yet).
Consider rephrasing your sentence, or upload different image / video using a less aggressive approach. The warning will disappear once Facebook algorithm finds your creatives compliant to its ad policies.
2. Your Website Domain Is Blacklisted
If you happen to be using a website which used to be an Expired Domain, make sure the website has not been used to advertise non-compliant items previously. While an Expired Domain may help to boost domain age and history, you have no control over what the previous owner has done to the website.
Do check the cache of the website before using it to advertise under your Business Manager. If you continue to receive "Ad May Not Run: Potential Policy Issue" after multiple attempt, consider switching your webstore or landing page to another new domain. The error message should disappear after the migration is completed.