The reason for that is that I chose a particular brush from the set of available brushes ('dry brush'). Since MNIST digits are quite sharp and opaque, the agent

The reason for that is that I chose a particular brush from the set of available brushes ('dry brush'). Since MNIST digits are quite sharp and opaque, the agent tries to achieve this by retracing the contours. I guess the remedy is to pick an appropriate brush style or make the agent choose it.