This refers to the resolution (1280x720). While 1080p and 4K are higher, a high-bitrate 720p file often looks better than a compressed 1080p stream because it retains more "clean" data per pixel.
If you are looking to understand what this string means or why it represents a superior viewing experience, Decoding the String: What You’re Getting tenet2020720p10bitimaxblurayhindidd51e extra quality
This specific keyword string——is a highly technical "scene" tag used in the digital media world. It describes a very specific version of Christopher Nolan’s 2020 sci-fi epic, Tenet . This refers to the resolution (1280x720)