Test page: https://learn.wordpress.org/test/wordpress-playground-block-plugin-test-page/

Every time the Playground block is used, it renders a <main> landmark. Really, this landmark should only be used once per page. Can this be replaced by another tag? Maybe just a generic <div>? You could also replace this with a <section aria-label="Playground"> but I think if the Playground block has surrounding headings, it's not a big deal.