Visibility of system status is the usability heuristic that is being used in this case. Visibility of system status means that the system should always keep users informed about what is going on, through appropriate feedback within reasonable time1. One way to apply this heuristic is to use visual indicators to let users know which form fields are required, such as asterisks, labels, or colors. This helps users to understand the expectations and requirements of the system, and to avoid errors or confusion. By providing clear and timely feedback, the system enhances the user experience and satisfaction. References: Learn About User Experience Design Unit | Salesforce Trailhead, [10 Usability Heuristics for User Interface Design], Salesforce User Experience (UX) Designer Certification Guide & Tips