Calendar app in Mac App Store mines cryptocurrency in the background

A calendar app in the Mac App Store has been mining cryptocurrency in the background in exchange for giving users additional features — and an option to opt out of mining has been broken. So far, Apple has not taken the scheduling app Calendar 2 down, even after Ars Technica informed the company that Calendar 2 has been mining virtual currency.
The app is supposed to be a buffed-up version of Apple’s Calendar app in macOS, but recently, its developer, Qbix, added extra code to mine