This bug is still reproducible on Ventura 13.1.1 and Safari 16.1.1 5 months later. I was wondering if this bug is relating to Apple's implementation of WebGL via Metal. I did an experiment that I run Bersaelor's test scene: https://test.looc.io/forest/index.html on Chrome 107 with metal as ANGELS backend. At last it's still with a freezing screen and 1-2 FPS on my M1 laptop. It seems that it's a Metal bug, and less relevant to WebKit.

As far as I know, though Macs are technically capable of being downgraded, there's no way of downgrading while keeping all your data. However, you could manually copy some of the customised files (e.g. ~/Library/Application Support) in your home folder and the particular Applications folder and then move them to the downgraded system without using Time Machine before. For Apple Silicon Macs, other than primary Recovery, you can use the new "Fallback Recovery" to go back to an old version of macOS. Remember you'll lose ALL your data after this. Boot into Fallback Recovery first. Here's a description of entering Fallback Recovery from https://eclecticlight.co/2023/03/02/recovery-on-apple-silicon-macs-has-changed-again/ "(T)he official way is the same as entering primary Recovery, only instead of pressing and holding the Power button once, you press it briefly first, then immediately press it again and hold it, with a di-dah rhythm and timing." Open the Disk Utility from the status bar. Erase the Macintosh HD Volume. Remember to choose the "Erase the Volume Group" when prompted to confirm erasing. Exit Disk Utility and go back to the main screen of Fallback Recovery. Now you can see the option of "Reinstall macOS Ventura" or "Reinstall macOS Monterey" option. Here to go.