The definition is overly broad because literally anything the user doesn't like can be blamed on bad UX design. It's too broad to be useful in understanding specific problems. It's like saying anything a person doesn't like in a restaurant was not cooked well.

Also user experience follows pretty heavily from UI design, you cannot separate the two without losing something. But "experience" is also much more subjective: Some might have a bad experience digging through menus while another person might have a good experience, like the way it's all organized. As an example, I found the notification for this issue perfectly acceptable: it let the user know a copy would be made. That is a pretty clear indication that the originals will still exist, and new ones would end up in Glacier. My experience there would be fine.

User experience is unhelpful in this respect because you cannot design your system to satisfy the experience of every user.