Maybe it's because he is usually bored in a cage and has nothing to play with, which will lead to his bad temper. After all, the space in the chipmunk cage is limited, so we can help him install a running wheel in the cage at ordinary times, which can be used by him to pass the time.
It may be because he is not satisfied with the food we feed him at ordinary times and doesn't like it, which leads to his abnormal temper.