Object detection and noise in train/obj_loss learning curve

I am training an object detection model using YOLO. After having added new annotated data, I observe something strange in the learning curves regarding "objectness". Though the train/obj\_loss learning curve is going down over time, it is quite noisy (train curve in blue, validation curve is in orange).

Previous models with less data it was much smoother. In fact, I would have expected the inverse, that there is less noise with more data. However, model performance with regards to mAP …

computervision detection learning noise