Android mobile apps can provide whole new experiences for users.
However, many innovative ones on Google's Play Store are built using APIs in ways that Google never intended. Android has allowed apps to modify the behavior of other apps using its Accessibility Services.
Accessibility Services, in general, refers to making Android apps more accessible to users with certain disabilities such as those who are visually impaired. While the intended purpose is to help users with disabilities, the API can also be used to improve experience for normal users, like filling text fields, remap volume keys to do something else, putting overlays and so forth.
App that wishes to use the Accessibility Service must add the permission to the AndroidManifest file so only the system can bind to the app’s service.
While Accessibility Services can greatly extend the functionality of apps, they have security risks.
Once granted the right permissions, the API can be used to read data from other apps.
This is the reason why Google Play Store team is sending out emails to developers that use the API, telling them that they can no longer implement Accessibility Services unless they follow Google’s guidelines.
What Google is doing, is starting to crack down on apps that are likely related to the growing issue of exploits that take advantage Accessibility Service.
The company us trying to stop apps from using Accessibility Service for any reason other than assisting users with disabilities.
The company is giving developers that use Accessibility Service on their apps a month to remove the permission, or will have their application removed from the Play Store. Failure to abide by this requirement can also result in an infraction against a developer’s Play Store account, which can eventually lead to account termination.
For apps that want to use the Accessibility Service, Google stated that developers need add a prominent, user-facing disclosure of the reason behind why their app needs the permission.
For developers of apps that do need Accessibility Service for a good reason. Like improving experience for normal users, there isn't much choice they can take.
They can either comply with Google’s demands by removing their Accessibility Service, or face Google's threat
Simply adding a disclosure for why their app uses Accessibility Service would only work if their app was legitimately aimed at assisting users with disabilities, which doesn’t describe most apps currently using Accessibility Service.