Which of the following is an example of poor UX design?

A form that clears all input if one field is filled incorrectly exemplifies poor UX design because it creates a frustrating experience for users. When users fill out a form, especially if it is long or requires detailed information, they expect that their work will be preserved, even if they make a mistake in one field. If an error occurs and the entire form resets, users are forced to re-enter all previously completed information, leading to feelings of annoyance and helplessness. This not only increases user frustration but can also lead to abandonment of the task or negative perceptions of the website or application, which is detrimental to user engagement and satisfaction.

In contrast, the other options represent good practices in UX design. Websites that load quickly enhance user experience by minimizing wait times. Consistent navigation patterns in mobile apps help users to easily understand how to interact with the app, making it more intuitive. Personalized user experiences are generally appreciated by users as they feel their needs are catered to, enhancing overall satisfaction and engagement with the digital product. These aspects contribute positively to user experience, while the first option clearly detracts from it.