How to reproduce:
1. Create and open a new project
2. Open Package Manager (Window > Package Management > Package Manager)
3. Install “Ads Legacy” package (com.unity.ads)
4. Import the “UnityAds Example App” sample, from the Samples tab
5. Open the “UnityAdsExample” scene
6. Enter Play Mode
7. Click “INITIALIZE” button
8. Click either of the “Show” buttons
9. Observe the Game view

Actual result: No placeholder screen, instead showing up white
Expected result: Placeholder screen is shown

Reproducible with: 4.16.3 (2023.1.0a3, 6000.3.6f1), 4.16.4 (6000.0.66f1, 6000.3.6f1, 6000.4.0b6, 6000.5.0a5)
Not reproducible with: 4.12.0 (2023.1.0a3, 6000.3.6f1)

Reproducible on: macOS 26.2 (M1 Pro)
Not reproducible on: No other environments tested