Flutter White screen of death. App loads fine in debug mode cant load in release mode(apk)

I have tried flutter clean, running FlutterError in the main method, running app in release mode, inserting internet permission in manifest file, changing compile and target sdks in the build.gradle file but no error is thrown and most of debug techniques but nothing works. Any help is welcome.

Below is my Splash Screen that loads initially

import 'dart:async';

import 'package:flyber/core/app_export.dart';
import 'package:flyber/presentation/onboarding_screen_seven_screen/onboarding_screen_seven_screen.dart';
import 'package:flyber/widgets/spacing.dart';
import 'package:flutter/material.dart';

class SplashScreensThreeScreen extends StatefulWidget {
  @override
  State<SplashScreensThreeScreen> createState() =>
      _SplashScreensThreeScreenState();
}

class _SplashScreensThreeScreenState extends State<SplashScreensThreeScreen> {
  void initState() {
    // TODO: implement initState
    super.initState();
    Timer(Duration(seconds: 3), () {
      Navigator.of(context).pushReplacement(
          MaterialPageRoute(builder: (_) => OnboardingScreenSevenScreen()));
    });
  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      top: false,
      child: Scaffold(
        backgroundColor: ColorConstant.primary,
        body: Column(
          mainAxisSize: MainAxisSize.max,
          crossAxisAlignment: CrossAxisAlignment.center,
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            VerticalSpace(height: 40),
            Align(
              alignment: Alignment.center,
              child: Text(
                Constants.appName,
                overflow: TextOverflow.ellipsis,
                textAlign: TextAlign.center,
                style: TextStyle(
                  color: ColorConstant.whiteA700,
                  fontSize: getFontSize(
                    28,
                  ),
                  fontFamily: 'Fira Sans',
                  fontWeight: FontWeight.w700,
                  letterSpacing: 1.12,
                ),
              ),
            ),
            Container(
              alignment: Alignment.center,
              margin: getMargin(
                bottom: 30,
              ),
              child: RichText(
                text: TextSpan(
                  children: [
                    TextSpan(
                      text: "Powered by",
                      style: TextStyle(
                        color: ColorConstant.whiteA700,
                        fontSize: getFontSize(
                          16,
                        ),
                        fontFamily: 'Fira Sans',
                        fontWeight: FontWeight.w400,
                        letterSpacing: 0.64,
                      ),
                    ),
                    TextSpan(
                      text: " Flyber",
                      style: TextStyle(
                        color: ColorConstant.whiteA700,
                        fontSize: getFontSize(
                          16,
                        ),
                        fontFamily: 'Fira Sans',
                        fontWeight: FontWeight.w700,
                        letterSpacing: 0.64,
                      ),
                    ),
                  ],
                ),
                textAlign: TextAlign.center,
              ),
            ),
          ],
        ),
      ),
    );
  }
}