Following in the footsteps of Apple and Chrome, Google Play has officially banned cryptocurrency mining apps from the store. This includes, but is not limited to, dedicated mining apps, apps and games that monetize through mining, and apps that mine without permission. This does not include apps that allow you to remotely manage mining operations, either on your own computer or on a cloud platform. It also does not prohibit apps that manage your cryptocurrencies themselves, like via wallets, etc.
Cryptomining has been known to cause physical problems to devices, especially when it is included in an app without the user's knowledge and consent. In those cases, devices can get incredibly hot, which can cause damage to the case and the screen. They also tend to draw a lot of power, which can eventually cause damage to the battery, including causing it to swell. A swollen battery puts unexpected pressure behind the electronics and can crack circuit boards, screens, and cases.
Unfortunately, this also has the effect of Google deciding what you can and cannot do with your device. Purposeful crypto mining on Android devices is not unusual, as many devices, especially devices like a Samsung flagship device, have incredibly powerful processors which can actually be semi-successful at mining., especially if you already have the device lying around. Creating a small farm of Android devices can produce decent results for an amateur miner. While no new apps will be allowed in the store, current mining apps will be removed at some point in the near future.
However, with this decision, Google has decided that, if you want to repurpose old technology, you are going to have to go through the trouble of sideloading miners, which could be riskier than allowing them in the store in the first place. Software in the Play Store gets scanned for malware, though with differing results, when it is in the store as well as once it is on your device. This helps prevent malware from affecting your device. In sideloading, there is no way to be sure it is safe. So, if you decide to use an Android device to mine crypto, be careful with sideloading software.