Am I being hacked? Is this on the up and up?

No, you are not being hacked.

No, it is not on the up and up.

If running iOS 13 or earlier versions, check: Settings - Passwords & Accounts - Accounts - Any rogue entries here? If so, delete the rogue account. 

If running iOS 14, check: Settings - Calendar - Accounts - Any rogue entries here? If so, delete the rogue account. 

The Apple support article is below. 

Remove calendar spam

Video support

Not sure what it is, but you are not being hacked. If you have a Safari popup, clear your browser.