There is a major usability regression in Mastodon 4: you can no longer access the link to a profile from the profile card on Mastodon Web without going into the kebob menu (the vertical ...) and clicking "Open original page"

The issue is being discussed here:
https://github.com/mastodon/mastodon/issues/20744, but I would personally recommend holding off upgrading to 4.0.2 until this is figured out cause this will cause many many issues on smaller instances. #MastoDev