Flutter: unable to load admob ads in flutter app

I have initialized admob using the admob plugin in my flutter app. Tested using testAdUnitId and everything works perfectly fine. Then I changed my testAdUnitId with the real one geneated from admob. Now when it comes to testing on real devices i tested it on android 5 and android 10. Thus the rewardedApp loads in mobile with Android version 5 but do not load in device with android 10. I have asked for internet persmission in AndroidMenifest.xml and my app also contains firebase authentication which works perfectly fine. Please help me if you can ! I am unable to find solution to this problem.