Apple's experimental browser that is used to test the news in it and then be able to incorporate them into the version of Safari that all users have, It has been updated to version 106. Four years ago this browser was introduced by Apple and we are still practicing with it and ensuring that the Safari functionalities will be suitable.
It's not that the new version brings news worth mentioning. Safari Technology Preview version 106 includes bug fixes and performance improvements for Web Inspector, Async Scrolling, Web Animations, CSS, JavaScript, WebRTC, Web API, Media and Rendering.
All of them very necessary, as we said so that the final version of Safari that later reaches users does not suffer from serious errors that make the user experience bad. Although versions of the browser are not always released without flaws or security holes ...
The new update is available both for macOS Mojave as for macOS Catalina and you can download the new version through the Mac App Store.
If you want you can check for yourself the notes that Apple has developed for this new update. You just have to enter the website created for it.
You already know that this version of Safari can run at the same time as the final version of Safari. So you can see first-hand if the updates are really useful for something, they are noticed or on the contrary they are only minimal. But for this it is better that you go to the notes of the update that Apple makes on the same and also of the previous versions
If you are a developer, this new update will interest you more than anyone else because you can see how the news that Apple is including is improving. What's more you can leave your comments on how you see these new improvements.