The computed instability index of each composition peaks at approximately 25% MA content, indicating more degradation occurs closer to the FA-rich compositions, but not at purely FAPbI 3 compositions. Through visual inspection of the degradation results, we manually threshold the instability index at I c > 10000 px •min to classify samples with high degradation rates, i.e., the samples with MA proportions between 10%-40%. Patterns of high stability in FA-pure perovskites that decrease as MA is added are seen within literature, for example when the samples are degraded under high heat and humidity , however, the trends in high-MA compositions are less clear from literature . The extracted instability index results are thus further validated via pre-and post-aging XRD (shown in the Supplemental Information). The post-aging XRD peaks of hexagonal FAPbI 3 first increase with increasing MA proportion but start to decrease after more than 50% of MA is added, which matches the degradation observed via the computer vision approach. At the same time, the other possible major degradation route via perovskite decomposition phase .