Weird calendar thing.
My calendar keeps giving me notifications for random things and they won’t go away. It also won’t let me delete them from my calendar. Have I got a virus in my phone?
iPhone 11 Pro, iOS 13
Are you seeing something as shown in pic below?
Then probably you have accepted an offer or subscribed for a spam Calendar accidentally. Watch the GIF below to know how to unsubscribe from these alerts. Look for an unknown Calendar on the device under subscribed calendars.