Flutter AdMob will not launch

Question

Trying to incorporate adMob into a flutter app and I am having this issue:

Launching lib/main.dart on sdk gphone64 arm64 in debug mode...
lib/main.dart:1
✓  Built build/app/outputs/flutter-apk/app-debug.apk.
E/AndroidRuntime(31743): FATAL EXCEPTION: pool-3-thread-1
E/AndroidRuntime(31743): Process: com.tendigitgrid.app_free, PID: 31743
E/AndroidRuntime(31743): java.lang.IllegalArgumentException: com.tendigitgrid.app_free: Targeting S+ (version 31 and above) requires that one of FLAG_IMMUTABLE or FLAG_MUTABLE be specified when creating a PendingIntent.
E/AndroidRuntime(31743): Strongly consider using FLAG_IMMUTABLE, only use FLAG_MUTABLE if some functionality depends on the PendingIntent being mutable, e.g. if it needs to be used with inline replies or bubbles.
E/AndroidRuntime(31743):    at android.app.PendingIntent.checkFlags(PendingIntent.java:375)
E/AndroidRuntime(31743):    at android.app.PendingIntent.getBroadcastAsUser(PendingIntent.java:645)
E/AndroidRuntime(31743):    at android.app.PendingIntent.getBroadcast(PendingIntent.java:632)
E/AndroidRuntime(31743):    at androidx.work.impl.utils.ForceStopRunnable.getPendingIntent(ForceStopRunnable.java:174)
E/AndroidRuntime(31743):    at androidx.work.impl.utils.ForceStopRunnable.isForceStopped(ForceStopRunnable.java:108)
E/AndroidRuntime(31743):    at androidx.work.impl.utils.ForceStopRunnable.run(ForceStopRunnable.java:86)
E/AndroidRuntime(31743):    at androidx.work.impl.utils.SerialExecutor$Task.run(SerialExecutor.java:75)
E/AndroidRuntime(31743):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
E/AndroidRuntime(31743):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
E/AndroidRuntime(31743):    at java.lang.Thread.run(Thread.java:920)

ANd it will not launch into the emulator to test.

I have minSDK set to 21 in my gradle file.

Update:

I tried installing the apk on my real phone and not in an emulator and it also did not work.