Decision Tree on Unbalanced Data
Which function are you using at Loss? Using the right one is important when dealing with imbalanced datasets. 7% is imbalanced, but not that bad. 

Have you tried any eXplainable Artificial Intelligence (XAI) method? Normally I use Shap.
It is really good to see which feature contributes in which direction. You can see an example here.



You can check the github here
You can check the paper here