Unusual banner is displayed when alarm goes off on iPhone 16 Pro

When an alarm goes off on my wife’s iPhone 16 Pro phone, sometimes an unusual banner is displayed that is white instead of the usual orange one with the ringing clock icon. My phone is identical, but doesn’t do this. No one from Apple support or the Genius Bar knows why.

[Re-Titled by Moderator]

Original Title: Strange banner for alarms. Not the usual one