Add calendar subscription pop-up message

I recently got a pop-up message asking me if I wanted a calendar subscription.

I could either tap ok or cancel. The phones functions itself was locked. The only way I could get the pop window to disappear, was by tapping the cancel-button.

my question is; Is the pop-up message itself an apple software/auto pop up message, and therefor, you can safely tap the cancel button or is the pop-up message in fact a scripted one from “the spammer” and therefor you should not have tapped cancel? I’ve looked in my calendar accounts and there’s no calendar names, that shouldn’t be there 🤞🏻

BR