An increasing number of reports from iPhone users about their calendars filling up with junk events. These events are most often either pornographic in nature, or claim that the device has been infected or hacked. In all cases, the content is a scam message trying to get you to open a link. If you have been impacted, your iPhone has fortunately not actually been hacked or infected (regardless of what the messages claim) There is a simple solution: delete the subscribed calendars youve seen.”]
Source: https://blog.malwarebytes.com/malwarebytes-news/2021/05/iphone-calendar-spam-attacks-on-the-rise/