I had only Linux PC with Intel GPU. And I could not reproduce the problem until now. The patch add logs. And with the STR, CanvasTranslator::PushRemoteTexture() was not called. Instead, SourceSurfaceCanvasRecording::GetDataSurface() was called sometimes. readback might have a problem with NVIDIA GPUs.
Bug 1907828 Comment 22 Edit History
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I had only Linux PC with Intel GPU. And I could not reproduce the problem until now. The patch add logs. And with the STR, CanvasTranslator::PushRemoteTexture() was not called. Instead, SourceSurfaceCanvasRecording::GetDataSurface() was called sometimes. readback of DrawTargetWebgl might have a problem with NVIDIA GPUs.