Yes, I also see it sometimes in case I’m hitting the invalid loss values.
In that case the gradient also seems to blow up, the scaler will skip the optimization step, and reduce it’s scaling factor.
You could manually check it via:
        s0 = scaler.get_scale()
        scaler.update()
        s1 = scaler.get_scale()
        if s0 != s1:
            print('skipped')