Sorry to say, it is difficult to answer your question, since your not certain of the varieties you planted.

With that said, I have never encountered a situation or read that the color of the peony blooms are affected by soil/ph conditions.

The only plant whose blooms are affected by ph condition are hydranges. There may be others, but I am not aware of them.

My other conjecture - and it is a conjecture - is that you may have some light pink or blush peonies whose blooms do rapidly turn to white. I once great "Mrs. F. D. Roosevelt" in central Illinois. From the photographs, her blooms were a nice pink. In my garden, they emerged as a light pink and turned to near white as the blooms matured.

I suspect that this may explain your situation, but, obviously, I am not certain.

Sorry, I couldn't be of greater assistance.

Bill