The search engine’s recommendation to maintain parity between AMP and canonical HTML pages does not apply to ads. Searchers would land on an AMP page, get a paragraph or two of content. Recently Google introduces a new rule to combat the problem of AMP being used as a teaser page. This leads searchers to land directly on-page, which is not an ideal user experience.
AMP was introduced to dramatically improve the performance of the web and deliver a fast, consistent content consumption experience. He also said few things about AMP content parity in which he said even within a normal HTML page, and you could have something like dynamic ads where sometimes you have an ad unit there, and sometimes over here.
When the Page Experience update rolls out in May, Google says regular HTML pages may be eligible for the Top Stories carousel if they meet the new Core Web Vitals thresholds. AMP page doesn’t contain the same critical content as its non-AMP equivalent. This does not affect Search ranking. However, these pages will not be considered for Search features that require AMP, such as the Top Stories carousel with AMP.” But If you’re going to use AMP, make sure the content matches the canonical HTML pages. Now we know it’s acceptable to show ads on AMP pages that aren’t on the canonical HTML pages, and vice versa.