If you’re trying out my https://view-transitions.netlify.app demos, not all of them work in Safari Technology Preview:
1. Most of my demos require the Navigation API to customize the VT based on where you came from. This API is only available behind a flag in STP. The demos now show a warning if support for something (VT Types, Navigation API, etc) is missing.
2. There seems to be a bug causing the page to become unresponsive after using the UA back/forward buttons. A bug was filed: https://bugs.webkit.org/show_bug.cgi?id=280703