Abundance ratio of HCOOCH₃ with respect to CH₃OH in HOPS-108 compared to other isolated hot corinos as a function of the class in no particular order within a given class (top) and HCOOCH₃ column density (bottom). The open symbols correspond to the sources where CH₃OH column density is most likely underestimated (see Sect. 4.2.1). The Class 0 sources are: IRAS 2A, IRAS 4A2 (Taquet et al. 2015; López-Sepulcre et al. 2017), B1-c, S68N (van Gelder et al. 2020), HH212 (Bianchi et al. 2017; Lee et al. 2019), L483 (Jacobsen et al. 2019), Ser-emb 1 (Bergner et al. 2019), IRAS 16293 A (Manigand et al. 2020), IRAS 16293 B (Jørgensen et al. 2016, 2018), HOPS-108 in OMC-2 FIR 4 (this work), and the sources from the PEACHES survey (Yang et al. 2021). The Class I sources are: Ser-emb 17 (Bergner et al. 2019), L1551 (Bianchi et al. 2020), and also sources from the PEACHES survey (Yang et al. 2021).