Why was my ad rejected?

There are many reasons. It is worth to study the rules of the server that such problems would not be

The reasons for deviation can be divided into four groups: Prohibited topics. You cannot advertise illegal substances, pyramid schemes, pirated software, counterfeit goods, offensive and dangerous content, etc. Prohibited Activities. You may not advertise fraudulent schemes, malicious software, deceive consumers, misrepresent product information, or collect confidential data Content and areas with restrictions. National law may restrict advertising of certain goods and services in some countries. Editorial violations. Spelling mistakes, overspam, generalizations, vague language, meaningless content, catchphrases. There may be other reasons, see https://newmediaservices.com.au/fundamental-basics-of-content-moderation/.