watchOS 10.4 Beta2 (21T5196d) broke its browser component! You can send youtube.com to your Apple Watch via iMessage, and then open it! Everything worked fine in the official version of watchOS 10.3; you couldn't watch videos because the Apple Watch's WebView doesn't have a video component, but you could at least browse web pages normally.
However, in watchOS 10.4, WebView is completely broken, and you can't even view the homepage recommendations or try searching for content properly — web pages refresh automatically within seconds and keep crashing repeatedly. Please revert everything back to the state of watchOS 10.3!
The minimal demonstration link to reproduce this bug:
https://ling-bucket.oss-cn-beijing.aliyuncs.com/apple/minimalVideo.MOV