Caveat emptor! Mine is freezing every two minutes! You do not seem to be able to uninstall it.
I reinstalled Catalina 10.15.6 and it was still there!!!!
I have contacted Seed admin. I have send at least 15 or more crash reports after Force Quit.
Try the Tech Preview first. I should have known better, since that was hanging just as much.
I have done all the usual including removing Caches, Containers, Prefs etc. I disabled all extensions, disabled Cross-Origin restrictions and so on. Nothing has made a difference.
Note that WebKit is also used by other apps like Messages.
Safari Technology Preview just updated today and is stable (release 110.)
If you are interested in the Big Sur features, get his first. You can use the General Preferences panel to make it the default.