Exactly what's been happening to me - I've been googling but I've been surprised I haven't seen more people reporting the same behavior.
Starting happening after the May release, doesn't appear to be fixed by the June release for me. Camera will be out of focus only on the main wide angle (108mp) lens, it's perfectly in focus when I switch to the other three. Tapping an object in the frame to get a focus lock on it does nothing, like it's stuck on a focus lock already that it won't give up. Force quitting the Camera app and clearing the cache often does nothing either.
What I've found to be most effective is putting my hand in front of the lens so that "Focus Enhancer" turns on (which I know is just it switching to the Ultra Wide), and then pulling my hand away. When it switches back to the main Wide angle, it's often focusing properly again but it's hit or miss and can take several attempts.
To the OP's post, really miss the moment in a lot of these cases struggling to get this focus. Anyone else experiencing this issue? Anyone have any other solutions?
For reference I'm using a Snapdragon version of the S21 Ultra.