A key observation was the missing ortho-nitrophenol in R1 step impurities. The presence of this impurity has been reported across multiple works . It is surprising that the ASKCOS impurity module could not predict this impurity. We attributed this absence to the training dataset bias, with most reactions in the literature reporting the majority products in the chemical scheme, while impurities and side-products are moved to the text, thus not forming a part of the model training.