• Android loads fine.

• iOS fails with No ad to show for real ad units (but test units work fine).

• Exception: Banner with getCurrentOrientationAnchoredAdaptiveBannerAdSize works on iOS.

• Using google_mobile_ads: ^6.0.0 with Flutter 3.32.5.

• Apps are already live.

This points to an ad-serving / configuration issue on iOS, not a code bug.

Here’s a checklist of things to verify:

1. Confirm ad unit setup in AdMob

• Make sure the iOS ad unit is created specifically as a 300x250 (Medium Rectangle), not banner or other type.

• Verify that you’re using the correct iOS ad unit ID (not accidentally Android’s).

2. iOS App Store linking in AdMob

• In your AdMob console → App settings, ensure your iOS app is linked to the correct App Store listing.

• Sometimes if it’s not linked or newly published, Google may not serve real ads yet.

3. Ad fill issues

The error Request Error: No ad to show means AdMob has no fill for that size / placement on iOS (not your code).

• For medium rectangle (300x250), fill is often lower than banners, especially on iOS.

• Adaptive banners usually get higher fill, which explains why that works.
  Try running the app for a few days — sometimes new iOS ad units take 24–48h before real ads serve.

4. SDK & Info.plist checks

Make sure you’ve added in ios/Runner/Info.plist:

<key>GADApplicationIdentifier</key>
<string>ca-app-pub-xxxxxxxxxxxxxxxx~xxxxxxxxxx</string>
<key>SKAdNetworkItems</key>
<array>
    <dict>
        <key>SKAdNetworkIdentifier</key>
        <string>cstr6suwn9.skadnetwork</string>
    </dict>
    <!-- Add all AdMob/AdManager SKAdNetworks -->
</array>

⚠️ Missing SKAdNetwork IDs can cause no ads on iOS.

5. Test with another iOS device / network

Sometimes certain placements don’t serve due to limited demand in your region. Try a VPN or another country to test fill.

6. Consider mediation

If you want higher fill for 300x250 on iOS, set up AdMob mediation with another network (like Facebook Audience Network or Unity Ads).

Summary:

• Your code is fine (since test ads + banners work).

• This is almost certainly no fill from AdMob for that format on iOS.

• Double-check ad unit setup, Info.plist SKAdNetwork entries, and App Store linking.

• If all is correct, wait a bit or consider using adaptive banners / mediation to increase fill.

Would you like me to give you the exact Info.plist SKAdNetwork IDs list you should include for AdMob iOS so you can confirm if that’s the missing piece?