Why is the EDR unstable? Is it a system bug?

I use a 14pro device, and the system is iOS16. According to the instructions of WWDC22, I integrated related attributes in my program. When playing HDR video, print the value of headroom, which is usually 1 and does not change. Later, I used the official program Radiance to detect whether the EDR was activated, but the actual performance is that there is no difference in the sample picture, only occasionally there is a change. At this time, I started my own program and found that the value of headroom will change, which is greater than 1. But I personally feel that the probability of this kind of EDR being activated is relatively small. Is this a system bug? I am very confused, because according to the documentation, the amount of code to enable EDR is actually very small, and it seems very simple.