One possible explanation for the negative impact of pretraining with the RGD1 dataset is the discrepancy between the pretrained and target domains-not only in the quality of data (GFN2-xTB vs. CCSD(T)-F12a) but also in the reaction types covered by the datasets. As illustrated in Figures and, the reaction distributions in the RGD1 dataset differ significantly from those in the target domain (high-level CCSD(T)-F12a reactions). Consequently, pretraining with the RGD1 dataset may have led to a set of weights that are more suited to the RGD1 reactions, but less applicable to the reactions in the target domain, even after fine-tuning with high-level data.