What are best practices for app uninstall measurement?

Android Uninstall Rates are much Higher than iOS. 

Average D30 uninstall rate in Russia is about 58% for Android, and only 24% in iOS.

If you want some more uninstall benchmarks, you can find them here.

Targetting users who uninstalled the game is tricky. A big game update can be a very good option, but it's important to analyze your pitfall (=events after which there's a big spike in uninstalls). Sometimes it can be a simple bug, sometimes it's more than that.

Unpopular oppinion I suppose :), but I'd argue that tracking "Uninstalls" is honestly not that important. I would focus 100% on retention instead.

I can see cases where Uninstalls are usefull for specific product development questions; for example when checking the impact of new feature releases and updates. But even then it would be much more interesting to learn the specific reasons that users have for uninstalling your app (related to crashes or issues?). And not necesarily the absolute number of Uninstalls. In general as a business/app metric I would much rather focus on retention. In theory, when people are uninstalling your app, it will show up in your churn. If your churn is high, you'll have a problem regardless of people having the app installed, uninstalled, reinstalled etc. If someone deleted your app and reinstalls it the same month, I guess he would still part of your MAU and customer base.