You can now see how many users remove your app from devices running iOS 12.3 or later.
Login to your Apple Developer account here: https://developer.apple.com/
Click the "Analytics" link:
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Select the app that you want to see Analytics information for.
Under the "Overview" area, scroll all the way to the bottom, where you will be able to see the metrics for "Total Downloads by Device":
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Click the down arrow close to the title, and select "Usage" then "Deletions" as you can see here:
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Done! You can now see how many users uninstalled the app on iPhones, iPads and Macs.