This is likely what "extra quality" refers to. A high-bitrate encode reduces "banding" in dark scenes (like the Gotham rooftops) and eliminates blocky artifacts in high-motion action sequences. The Role of HDR (High Dynamic Range)
The 2017 theatrical cut of Justice League had a notoriously turbulent production, with cinematography shifts between Zack Snyder and Joss Whedon. Because the film features heavy CGI—especially the villain Steppenwolf and the final battle in Russia—standard compression can often make these effects look "muddy." movies4uvipjusticeleague20172160p4kuhd extra quality
It is worth noting that while the keyword specifies the version, many fans also seek out Zack Snyder's Justice League (2021). The 2017 theatrical version is snappier, more colorful, and runs about 2 hours, whereas the 2021 version is a 4-hour epic in a 4:3 aspect ratio. If you are a completionist, having the 2017 version in 2160p is the only way to see the original theatrical vision with modern clarity. Conclusion This is likely what "extra quality" refers to
Essential for the moody, shadow-heavy aesthetic of the DC Extended Universe. Because the film features heavy CGI—especially the villain