As discovered by Reddit user Penguin9003 in their Reddit post, a fan made version of 88 Degree Bedrock Rap is now circulating around as an ad for the official Honkai Star Rail game.
The clarification comes from user mouhappai in his comment stating that the ad being featured is not an official HoYoverse video, but the work of some talented individuals who uploaded the content on bilibili.
88 Degrees Bedrock Rap is part of a quest where the Trailblazer will need to get clearance from a couple of robots to enter Svarog’s compound. Clearance could either be obtained by either answering questions correctly or battling the robots with the contents of the rap hold the answers that will allow you entry to the compound peacefully.
Considering that the ad is in Chinese it is mainly targeted to a Chinese userbase. However, many are citing that they have seen the content being used as an ad regardless, as per YouTube user, Justin Thaw Set Myo and D Quade have stated in their comments.
The Honkai Star Rail official account has also commented on the bilibili video, which may mean that the fan video appearing as an official ad might be the product of a deal between HoYoverse and the creators of the video.
Honkai Star Rail is now available on Android, iOS and PC and has recently revealed future content coming in its 1.1 version update. For further information regarding the game, you may refer to their official website.