Yongnuo flashes and color temperature

I was looking up information on the YN560 IV and YN568EX II and trying to find information about their color temperature. The only thing I found is that it should be 5600k.

Should that mean that a 1/1 the temperature should be 5600k and there on all the way to 1/128?

I'm finding that it varies a lot from 1/1 to 1/128, for example I found that the YN560 IV at 1/1 was 6420 at 1/8 was 6740 and at 1/128 was 6490

I have two YN560 IV and found that the results were very similar between the two, they varied only 100k from each other.

Comparing them to the YN568EX II the temperature jumped a ton. The 568EX II at 1/128 was 6200!

I'm not really looking for exact color accuracy from those but I'm wondering why would they say that the temperature is 5600k if it's actually far from it.

I don't know how they compare to the Canons at each shutter speed, but the AWB on Canon cameras takes the flash duration of the Canon flash into account when setting the value.