What is a common accessibility issue found during manual testing related to keyboard navigation?

A common accessibility issue during manual testing related to keyboard navigation is the visibility of keyboard focus. When users navigate a website or application using only a keyboard, it's crucial that they can see which element is currently focused. If keyboard focus is not visible, users may not be able to determine where they are in the interface, which can lead to confusion and hinder their ability to interact with content effectively. This means that the lack of visible focus indicators presents a significant barrier for users who rely on keyboard navigation, particularly those with visual impairments who may not use a mouse.

In contrast, correct tab order ensures that users can navigate through interactive elements in a logical sequence, but it doesn't address the visibility of focus. Likewise, properly described images contribute to overall accessibility but are unrelated to keyboard navigation specifically. Filling all form fields is important for form completion but does not relate to keyboard navigation issues either. Thus, the visibility of keyboard focus is critical for ensuring that all users, especially those with disabilities, can navigate and interact with web content efficiently.