These websites are notorious "pirate release groups" that specialize in leaking copyrighted content. Historically, sites like FilmyWap started as mobile-focused hubs for small video files but have since evolved.
HEVC files are complex codecs. Pirate sites disguise executable viruses as .mkv files or force you to download a "codec pack" to play the video. This software is often ransomware or keyloggers that steal banking credentials.
While the film received critical acclaim, including five nominations at the 70th Filmfare Awards