The intensity at t = 0.2 s could have been manually compared to the standard deviation of normalized intensities, but we opted for a more elegant automated solution using UMAP dimensionality reduction. In essence, all individual curves from Fig. , representing normalized intensity vs. time, were transformed into single points in a new coordinate system defined by UMAP axes 1 and 2 (see the SI for detailed explanation). According to the rules of this transformation, curves with similar patterns are represented as a single cluster of points, while distinctly different patterns, such as those associated with pitting, form separate clusters. This behavior is precisely observed in the UMAP projection shown in Fig. . At t = 0.2 s, only one cluster of points is visible, indicating that the small decrease in intensity at this time remains within the standard deviation of normalized intensities. However, at t = 0.4 s, two distinct clusters appear, with the new cluster, depicted in orange, corresponding to pit formation.