Rocket Validator looks for accesibility violations on your pages using the axe-core accessibility engine, hosted on our own servers and integrated into our web crawler. You don't need to buy an additional license, everything's already included in your Pro account at Rocket Validator.
A11Y check: Main landmark must not be contained in another landmark
Accessibility rule: It is a best practice to ensure the main landmark is not contained within another landmark. All content should be contained within distinct regions such as the header (role='banner'), content (role='main'), and footer (role='contentinfo').