The story
From potty + learning, by analogy with potty training. The choice of learning is to suggest that a child must be taught to use the potty rather than explicitly trained (i.e. “forced”) to do so.
Etymology from Wiktionary, CC BY-SA 4.0.
potty learning
Today it means: A method of potty training in which a child is taught how to use the potty at their own pace and with much leniency, such as not utilising punishments or rewards, and with an emphasis on the child's independence. Full definition →