[Android] Ads flickering when navigating or scroll

import 'package:flutter/material.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';
import 'package:net_reven/app/config.dart';

class CustomBannerAd extends StatefulWidget {
  const CustomBannerAd({Key key}) : super(key: key);

  @override
  _CustomBannerAdState createState() => _CustomBannerAdState();
}

class _CustomBannerAdState extends State<CustomBannerAd> {
  BannerAd _anchoredAdaptiveAd;
  var _isLoaded = false;
  Orientation _currentOrientation;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();

    _currentOrientation = MediaQuery.of(context).orientation;
    _loadAd();
  }

  @override
  void dispose() {
    super.dispose();

    _anchoredAdaptiveAd?.dispose();
  }

  Future<void> _loadAd() async {
    await _anchoredAdaptiveAd?.dispose();

    if (mounted) {
      setState(() {
        _anchoredAdaptiveAd = null;
        _isLoaded = false;
      });
    }

    final AnchoredAdaptiveBannerAdSize size =
        await AdSize.getCurrentOrientationAnchoredAdaptiveBannerAdSize(
            MediaQuery.of(context).size.width.truncate());

    if (size == null) {
      debugPrint('Unable to get height of anchored banner.');
      return;
    }

    _anchoredAdaptiveAd = BannerAd(
      adUnitId: Config.adUnitId,
      size: size,
      request: const AdRequest(
        nonPersonalizedAds: false,
      ),
      listener: BannerAdListener(
        onAdLoaded: (Ad ad) {
          debugPrint("Ad loaded");
          if (mounted) {
            setState(() {
              _anchoredAdaptiveAd = ad as BannerAd;
              _isLoaded = true;
            });
          }
        },
        onAdFailedToLoad: (Ad ad, LoadAdError error) {
          debugPrint('$BannerAd failedToLoad: $error');
          ad.dispose();
        },
        onAdOpened: (Ad ad) => debugPrint('$BannerAd onAdOpened.'),
        onAdClosed: (Ad ad) => debugPrint('$BannerAd onAdClosed.'),
      ),
    );

    return _anchoredAdaptiveAd.load();
  }

  @override
  Widget build(BuildContext context) {
    return OrientationBuilder(builder: (context, orientation) {
      if (_currentOrientation == orientation &&
          _anchoredAdaptiveAd != null &&
          _isLoaded) {
        return Container(
          color: Colors.transparent,
          width: _anchoredAdaptiveAd.size.width.toDouble(),
          height: _anchoredAdaptiveAd.size.height.toDouble(),
          child: AdWidget(ad: _anchoredAdaptiveAd),
        );
      }

      // Reload the ad if the orientation changes.
      if (_currentOrientation != orientation) {
        _currentOrientation = orientation;
        _loadAd();
      }
      return const SizedBox.shrink();
    });
  }
}