I'm not able to tell you whether it was born like that or if it sustained an injury at a young age.
I know that some hatcheries/breeders will cut the tails off fish intentionally and market them as "Heart-Shaped", it is a cruel practice.
I doubt that this is one of those, If I had to guess I would say the tail was damaged/destroyed early on in the development of this fish.
It does make her cool and unique. And I like that.
For that reason I would advise against finding a male and breeding this fish. Convicts do breed very easily, a lot of people say "just add water" and they will breed. The problem is convicts, like most CA cichlids, have the potential to get violent toward each other when breeding, I had a very nice female con get ripped to shreds post spawn. She had her tail bitten off, and it may never heal.
Another reason I would advise against breeding them is they will almost certainly get violent with any other tankmates when they breed. A pair of Cons will fend of fish 2 or 3 times their own size in defense of their spawn point.
She should not lose any of her color, in fact, as long as you have her on a good diet, her colors may get more intense.
They are a fun fish.
Be advised:depending on her size any guppies you decide to put in with her may become snacks.