@ptrblck, thank you for the reply.
I know, the class 0 has increased even more now, but the problem is that the class 0 appears in every single image as it refers to background, so it is inevitable I think if I use oversampling(with a few augmentation methods) technique.
I am currently training my model, but seems that the training iou has significantly increased but not so much with the validation iou yet.
Do you think I shouldn’t use the oversampling with augmentation technique in my application and rather leave my original dataset as it was?