The URL Rating (UR) and Domain Rating (DR) are separate metrics in Ahrefs, and they measure different aspects of a site's backlink profile. It's possible for a page's UR to be higher than the site's DR due to the following reasons:
Quality of Backlinks: If a specific page has attracted high-quality backlinks from authoritative sites, its UR can be higher than the site's DR.
The concentration of Backlinks: If most backlinks point to one particular page rather than being spread across the domain, the UR for that page can be higher than the DR.
Relevance of Backlinks: The page might be linked from highly relevant and authoritative pages in the same niche, which can boost its UR.
Remember, these are just estimations provided by Ahrefs and they don't necessarily reflect the way search engines like Google perceive the page or the site. But they can be useful for SEO analysis and decision-making.