Before revision:  However, a significant generalization gap in the robustness obtained from AT has been problematic, making practitioners to consider a bag of tricks for a successful training, e.g., early stopping  .
After revision:  However, the phenomenon of robust overfitting, i.e., the robustness starts to decrease significantly during AT, has been problematic, making practitioners to consider a bag of tricks for a successful training, e.g., early stopping .