Apps facilitating cryptocurrency trading need to come from properly licensed providers where required, wallet apps have to be from a developer enrolled as an organization, and actual on-device crypto mining isn't allowed at all — only cloud-based mining services can be offered.
Most often caught by an app attempting on-device mining, or a crypto exchange app submitted from an individual developer account rather than a licensed organization.
"Your app facilitates the mining of cryptocurrency directly on-device, which is not permitted per guideline 3.1.5."