With the exception of Watch OS 8.4, which notes it fixes an update for some chargers not charging correctly, these updates are all about security patches. This include the Safari bug that would allow websites to access your browsing history, including Google ID, but there is another fix that would allow a hacker to access your webcam through a web archive file downloaded to your machine without your knowledge. All these issues, among others, have been fixed in the latest security patch. Patches have also been ported to Catalina via Security Update 2022-001 and Big Sur in the 11.6.3 update.
Full patch notes can be found on Apple’s Security Updates page.