Usually, you would only see this under very low light conditions, as the exposure is maxed out and the analog gain gets to the max.
In JeVois inventor, can you first select a module with 30fps, for example, TensorFlowEasy, and then go to the "Camera" tab and try manual exposure and manual gain, then switch back to auto exposure and gain (note that both parameters are coupled). Sometimes some module sets the camera to manual mode (e.g., the modules that do color blob detection), and it will stay like that until you set it back to auto (or restart the camera).