There are a number of common UX/UI design mistakes that can adversely affect the user experience. One of the most common is failing to understand the user’s needs and goals. This can lead to designs that are either too complex or too simplistic, making it difficult for users to achieve their goals. Another common mistake is failing to take into account the user’s context, such as their physical environment, their prior knowledge, and their current state of mind. This can lead to designs that are confusing or unusable.

Another frequent mistake is designing for the wrong platform. This is often seen in responsive design, where designers fail to account for the fact that users on different devices will have different needs and expectations. This can lead to a poor user experience on both desktop and mobile devices.

Finally, a common mistake that can adversely affect the user experience is using low-quality or poorly designed assets. This includes using low-resolution images, using inappropriate fonts, and using cluttered or busy layouts. These design choices can make it difficult for users to understand and use your product, leading to frustration and a poor user experience.