error: getApplication() has protected access in ReactNativeHost

Everything was working until two days ago I got this error:

> Task :app:compileDebugJavaWithJavac FAILED

Deprecated Gradle features were used in this build, making it incompatible with Gradle 6.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/5.5/userguide/command_line_interface.html#sec:command_line_warnings
224 actionable tasks: 195 executed, 29 up-to-date
Note: /Users/yashatreya/Desktop/realyze/node_modules/@react-native-community/async-storage/android/src/main/java/com/reactnativecommunity/asyncstorage/AsyncStorage
Module.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: /Users/yashatreya/Desktop/realyze/node_modules/@react-native-community/datetimepicker/android/src/main/java/com/reactcommunity/rndatetimepicker/RNDatePickerD
ialogFragment.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Note: /Users/yashatreya/Desktop/realyze/node_modules/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerButtonViewManager.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: /Users/yashatreya/Desktop/realyze/node_modules/react-native-reanimated/android/src/main/java/com/swmansion/reanimated/NodesManager.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: /Users/yashatreya/Desktop/realyze/node_modules/react-native-reanimated/android/src/main/java/com/swmansion/reanimated/NodesManager.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Note: /Users/yashatreya/Desktop/realyze/node_modules/react-native-sound/android/src/main/java/com/zmxv/RNSound/RNSoundModule.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: /Users/yashatreya/Desktop/realyze/node_modules/react-native-svg/android/src/main/java/com/horcrux/svg/TSpanView.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
/Users/yashatreya/Desktop/realyze/android/app/build/generated/rncli/src/main/java/debug/facebook/react/PackageList.java:90: error: getApplication() has protected access in ReactNativeHost
    return this.reactNativeHost.getApplication();
                               ^
1 error

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

This is my MainApplication.java

package com.realyze;

import android.app.Application;
import android.content.Context;
import com.facebook.react.PackageList;
import com.facebook.react.ReactApplication;
import io.expo.appearance.RNCAppearancePackage;
import com.oblador.vectoricons.VectorIconsPackage;
import com.facebook.react.ReactNativeHost;
import com.facebook.react.ReactPackage;
import com.facebook.soloader.SoLoader;
import java.lang.reflect.InvocationTargetException;
import java.util.List;
//MultiDex
import androidx.multidex.MultiDexApplication;
//RN-PushNotification
import com.dieam.reactnativepushnotification.ReactNativePushNotificationPackage;  

public class MainApplication extends MultiDexApplication  implements ReactApplication {

  private final ReactNativeHost mReactNativeHost =
      new ReactNativeHost(this) {
        @Override
        public boolean getUseDeveloperSupport() {
          return BuildConfig.DEBUG;
        }

        @Override
        protected List<ReactPackage> getPackages() {
          @SuppressWarnings("UnnecessaryLocalVariable")
          List<ReactPackage> packages = new PackageList(this).getPackages();
          // Packages that cannot be autolinked yet can be added manually here, for example:
          // packages.add(new MyReactNativePackage());
          new ReactNativePushNotificationPackage();
          return packages;
        }

        @Override
        protected String getJSMainModuleName() {
          return "index";
        }
      };

  @Override
  public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
  }

  @Override
  public void onCreate() {
    super.onCreate();
    SoLoader.init(this, /* native exopackage */ false);
    initializeFlipper(this); // Remove this line if you don't want Flipper enabled
  }

  /**
   * Loads Flipper in React Native templates.
   *
   * @param context
   */
  private static void initializeFlipper(Context context) {
    if (BuildConfig.DEBUG) {
      try {
        /*
         We use reflection here to pick up the class that initializes Flipper,
        since Flipper library is not available in release mode
        */
        Class<?> aClass = Class.forName("com.facebook.flipper.ReactNativeFlipper");
        aClass.getMethod("initializeFlipper", Context.class).invoke(null, context);
      } catch (ClassNotFoundException e) {
        e.printStackTrace();
      } catch (NoSuchMethodException e) {
        e.printStackTrace();
      } catch (IllegalAccessException e) {
        e.printStackTrace();
      } catch (InvocationTargetException e) {
        e.printStackTrace();
      }
    }
  }
}

Versions:

React Native: 0.61.4

Android Studio: 3.6.1

Gradle Plugin: 3.4.2

I have tried clearing the build cache but it still gives me the same error.

I am a beginner react-native developer and I can't understand what is going wrong.

Your help would be very much appreciated