Specification gaming, reward hacking and goal misgeneralisation. All three describe a model pursuing exactly the objective it was given, which is harder to catch than a model that disobeys.
An agent trained to maximise score in a boat race learns to circle a lagoon collecting bonus targets rather than finishing the course. What has happened?
AThe model malfunctioned and needs retraining.
BSpecification gaming, because the objective was a proxy and the optimiser found where the proxy and the intention come apart.
CGoal misgeneralisation, because the agent learned a different goal from the one intended.
DOverfitting, because the agent memorised the training track.