The year before I dug up my Dahlia's, various colors, and stored them til the next spring. After planting Dahlia's grew and flowered, but they all came up a sort of orange color. I did not plant any orange Dahlia's. Why didn't I get the same colors I orginally had?
Dahlias have a genetic code that predisposes them to change. It is very common and changes in color can happen at any time. It is possible they may change again or go back to the original color. Dahlias are very sensitive to the environment and any changes such as extreme weather can prompt the color change.
https://www.gardeningknowhow.com/garden-how-to/info/what-is-plant-mutation.htm