Banner is being cropped with Prebid

[Hyungon Kim]

We are facing an issue where banners are width-cropped when rendered by Google Ad Manager (GAM) — but only when Prebid wins the auction.

Key Points

• Affects all platforms (React Native / Android / iOS)

• Not SSP-dependent — reproducible with multiple SSPs

• Not slot-dependent — happens on any banner position

• Not creative-related — HTML renders correctly when loaded manually

• Mostly occurs during German daytime

• Only happens when GAM renders a Prebid-winning bid, not a GAM-winning one

  → Please test with German VPN during business hours

Resources

• Repro project: https://github.com/hyungonkim-StroeerNZ/GamResizeFailTest

• Screenshot and usage instructions are included in the repository

Marcus B. from Google technical support has reviewed it and confirmed the GAM server is functioning normally.