This is likely a specialized internal tracking code or a "release group" tag used by the site to categorize their specific encodes. 2021: Refers to the release year of the content.
Sites like SkymoviesHD are notorious for intrusive pop-up ads and "invisible" download buttons. Clicking these can result in the installation of ransomware, spyware, or adware on your device. IMVBDXSKMHD -2021- www.SkymoviesHD.Red Unrated ...
Using these specific search terms to find and download media comes with several significant risks: This is likely a specialized internal tracking code