Coming in 8.9
In the process of fixing an issue with the ad rewards on mobile devices, we will be updating the software related to it.
Unfortunately, due to updating this software as a requirement, it will mean that devices that cannot be updated beyond Android 5.1 (from 2015) or iOS 12 (2018) will no longer be able to run Gems of War as of 8.9.
Older devices, over time, lose their ability to meet minimum requirements for apps/games, but I wanted to call this out as we specifically have the information on exactly what will prevent a device from running Gems of War.