https://wccftech.com/apple-bans-cryptocurrency-mining-apps/

Apple has announced new App Store restrictions, banning the use of cryptocurrency mining apps on iPhones and iPads. “Apps may not mine for cryptocurrencies unless the processing is performed off device (e.g. cloud-based mining),” Apple’s new App Store guidelines say.

In a separate clause on designing power efficient apps, the company said that “apps should not rapidly drain battery, generate excessive heat, or put unnecessary strain on device resources,” adding that they “may not run unrelated background processes, such as cryptocurrency mining.” This hints that the decision to ban mining apps from the App Store could have been taken to preserve battery performance.