Color–color diagram of the dusty source of the S-cluster and IRS13 (in gold). Although the IRS13 sample is slightly larger compared to the S-cluster objects investigated in this work, both groups of dusty sources show similarities, implying a shared nature. Especially the dusty sources of the S-cluster seem to share a comparable photometric footprint. All uncertainties reflect the standard deviation of the related magnitude estimated for all available epochs between 2006 and 2019. The linear gray fit represents a one-component blackbody. Based on this classification, we conclude that the majority of dusty sources exhibit colors that are consistent with a YSO classification. As a comparison, we include the H–K and K–L colors for several main-sequence and AGB stars from Blum et al. (1996), Ott et al. (1999), Pott et al. (2008), and Peißker et al. (2023b).