Apple sends the following warning by email when I upload a new version of the app:

ITMS-90809: Deprecated API Usage - App updates that use UIWebView will no longer be accepted as of December 2020. Instead, use WKWebView for improved security and reliability. Learn more (https://developer.apple.com/documentation/uikit/uiwebview).

I believe we don't actually use UIWebView -- we switched to WKWebView in 24.0.113, over a year ago. Unless we messed that up somehow. But react-native-webview at the version we're using still has code that refers to the old UIWebView, which is almost surely enough to explain the warnings.

Looks like I started getting these warnings with the upload of 26.23.146, on 2020-03-09. That may reflect a change in our app then, or it may just reflect Apple starting to issue these warnings.

It looks like react-native-webview dropped UIWebView in v7.0.1:
https://github.com/react-native-community/react-native-webview/releases/tag/v7.0.1

So we should upgrade to that version, and then see if that eliminates this warning.

That version in turn comes after the r-n-webview v6 change to use AndroidX. So after we ourselves migrate (#3852), we should be able to try that upgrade.