Zoom in to the C₄H₂ quasi-continuum of the maximum likelihood model for the retrieval presented in Sec. 3.3 (upper panel), the retrieval restricting the C₄H₂ flux (middle panel), and for the retrieval focussing only on the wavelength region from 12 μm to 17 μm (lower panel). The JWST/MIRI spectrum of Sz 28 is shown in black, with the molecular contributions to the maximum likelihood model being shown in different colours.