KeyboardAvoidingView mistakingly adds white space on screen bottom after being untangled

[Description]

I wrapped a view as a footer inside KeyboardAvoidingView. It works properly before the keyboard has been untoggled. However, after the keyboard is untoggled, it adds a white space on the bottom of the screen. The height of the white space is as big as the keyboardVerticalOffset. This white space shouldn't exist.

React Native version:

System:
OS: macOS 10.15.6
CPU: (8) x64 Intel(R) Core(TM) i7-7920HQ CPU @ 3.10GHz
Memory: 28.43 MB / 16.00 GB
Shell: 3.2.57 - /bin/bash
Binaries:
Node: 12.18.1 - /usr/local/bin/node
Yarn: Not Found
npm: 6.14.5 - /usr/local/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
Managers:
CocoaPods: 1.9.3 - /usr/local/bin/pod
SDKs:
iOS SDK:
Platforms: iOS 13.6, DriverKit 19.0, macOS 10.15, tvOS 13.4, watchOS 6.2
Android SDK: Not Found
IDEs:
Android Studio: Not Found
Xcode: 11.6/11E708 - /usr/bin/xcodebuild
Languages:
Java: 14.0.1 - /usr/bin/javac
Python: 2.7.16 - /usr/bin/python
npmPackages:
@react-native-community/cli: Not Found
react: ~16.11.0 => 16.11.0
react-native: https://github.com/expo/react-native/archive/sdk-38.0.1.tar.gz => 0.62.2
npmGlobalPackages:
react-native: Not Found

Steps To Reproduce

Provide a detailed list of steps that reproduce the issue.

1. Use KeyboardAvoidingView, set keyboardVerticalOffset to any value
2. Put a view inside KeyboardAvoidingView, set the position as absolute, and set the bottom to 0

Expected Results

The white space for keyboardVerticalOffset should only exist when the keyboard is toggled.

Snack, code example, screenshot, or link to a repository:

<KeyboardAvoidingView
      behavior={Platform.OS == "ios" ? "padding" : "height"}
      keyboardVerticalOffset={48}
      style={{width: "100%",
                   height: "100%",
                   position: "absolute",
                   zIndex: 1,}}
>
      <View
              style={{width: "100%",
                            position: "absolute",
                            height: 56,
                            bottom: 0,}}
      >
              <SubmitButton/>
       </View>
</KeyboardAvoidingView>

まず、behaviorをpaddingまたはheightに設定し、keyboardVerticalOffsetを48に設定した状態で、iOS上で提供されたKeyboardAvoidingViewの例を再現します。KeyboardAvoidingViewの実装を調査し、キーボードが表示されている間だけ下部のスペースが現れることを確認してから、キーボードを閉じた後に、提供された絶対位置指定のfooterが正しく動作することを確認します。