When I first started keeping shrimp years ago, was the only time I ever had my shrimp interbreed and revert to wild coloration. I had one 20g tank mixed with between 50-80 cherry, snowball, and blue pearl shrimp. After about 6 months to a year I noticed that slowly and surely my tank was being populated with unusually (wild) colored shrimp. By the time that three years had passed, my tank was filled with more crossbred shrimp than not. It is not an immediate transformation, it takes a few generations of interbreeding for the coloration to change.
The cherry shrimp turned kind of brownish/dark red
The blue pearl/snowball shrimp (different color morphs of the same shrimp) turned a brownish/gray color.