Question Unity Admob Test Ads not working on Android Device.

I have a game that has been published on Playstore for a year now with working ads. Previously It had a native ad plugin I removed the native ad plugin and added a simple google ads plugin because I am not using native ads anymore. Since then the ads are not working on android devices. They don't even load. Not Even the test ads are working. The ads work perfectly fine in the editor but when I build and apk even the test ads don't load on the android device. I tried changing unity versions. Tried different plugin versions of Google Admob nothing worked. Once I imported my game into a new project but the package name had a mistake only then the test ads work on My android device but once I fixed my package name the ads are not working now. Not even with the wrong package name that they worked with previously.