ITMS-90809: Deprecated API Usage Issue :
If you have received an email from The App Store Team regarding ITMS-90809: Deprecated API Usage issue, there’s absolutely no need to panic.
Though Apple has communicated their intent to deprecate API usage but has not yet come up with a solution to replace it, hence there is no need for you to do anything or take any action.
For more details you can take a look at their Developer Portal - https://developer.apple.com/documentation/uikit/uiwebview
As soon as Apple brings forth a solution, Appy Pie will bring you a customized solution to keep your app running smoothly.