iOS: Relevance Score

From iOS 15, Apple has introduced the relevance-score field for iOS push notification payloads. It is designed to be used in conjunction with the new 'Notification Summary' that can be used to group notifications received into regularly scheduled summaries. The relevance score helps the device to determine the relative importance of your notifications and display them accordingly in the summary. Note that other factors, including adding an image, will also impact the importance.