I am a full stack developer, and a very experienced and talented programmer. I know exactly how a system like this would work, and I would say that a “glitch” like this is highly unlikely, bordering on impossible. We’re talking “a solar flare caused a particle to flip a bit in the hardware” type of event. A “bug” in the system, highly unlikely as well, but possible, however this type of bug should be traceable and should have been found and fixed, and probably revealed a long long time ago.

The much more plausible reason is “human error”, or even more likely, fraud.