There’s no malware here, just a far mire mundane subscribed calendar filled with spam. Some website likely offered notifications, and that via a subscribed calendar, and the subscribed calendar spam-filled. Remoce the subscribed calendar.
Tap or click on the following blue-text link, and see all about how to Delete spam calendars and events on iPhone - Apple Support (but because you’re still apparently on iOS 13, you’ll need to use the Settings > Passwords & Accounts > Accounts path to find and remove the subscribed calendar.
I’d also update to iOS 14 if you’re concerned about security, as your footer here indicates iOS 13.
There’s no spyware to remove, no compromise of security, no further steps needed, just the removal of a subscribed calendar filled with advertising.
And as it’s very common, here are some of the many sorts of scams > Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support. These scams are far more common than actual malware, which is still quite rare for iPhone and iPad.