Sometimes a notification got "newly mounted" while being old. This can happen when a user has many notifications (100-1). The UI first only loads (100-76), if any notification is then resolved (e.g. by deleting or reading a chat), further old notifications (75+74) would be added to the UI and triggered a web notification (including call sound) in the past.
This threshold ID is therefore updated to only higher values, before each pulling of notifications to ensure that we only ever web-notify on new notifications and not newly loaded old notifications.
Sometimes a notification got "newly mounted" while being old. This can happen when a user has many notifications (100-1). The UI first only loads (100-76), if any notification is then resolved (e.g. by deleting or reading a chat), further old notifications (75+74) would be added to the UI and triggered a web notification (including call sound) in the past.
This threshold ID is therefore updated to only higher values, before each pulling of notifications to ensure that we only ever web-notify on new notifications and not newly loaded old notifications.