Gemini Flash 2.0 Lite: Unable to control image/video resolution, always processes at medium quality

Using Gemini 2.0 Flash Lite for image and video inputs on Vertex AI. Despite sending videos at 4K (25 fps) and 360×294 (1 fps), the model consistently processes inputs at medium resolution. Attempts to set the parameter mediaResolution to “low” have no effect Gemini defaults back to medium.
I would like to confirm if this fixed medium-resolution behavior is expected, and whether there is any way to override it to force low-resolution processing.