I have transplanted 3 peonies bushes from where my parents live to my home , these bushes are over 40 years plus. This year they all bloomed beautiful but are not what I took a few years back . the one know is a lovely pink with a ring of dark pink around the top of the pedal. the wife ones are now a tint of pink with the flowers all different from rounded edges to sunbursts and then one just one has this beautiful pink and yellow inside. I am having a feeling the bee’s had something to do with some of this ? can other plants I ut them near make them change . two others look the dyed and one is a beautiful soft pink.
Peonies don’t really like to be transplanted and the stress and change in soil and light conditions might cause the color of the flowers to change a bit. Changes to the actual shape of the petals is another thing entirely. Peonies don’t breed true to form from seed so it is possible that you have the offspring of the originals that grew from seed and took over the clumps of the originals before you moved them.