Top-left panel – SED of source 238 from 0.4–3 μm. NIRSpec spectrum, with uncertainty represented by error bar (black). HST photometry (grey). Phoenix stellar model (red). Bottom-left panel – Normalised NIRSpec spectrum (black). Phoenix stellar model (red). Best-fitting model shows no metal absorption lines, consistent with the NIRSpec spectrum. All hydrogen absorption lines are filled in by emission. We have removed the bump at 1.71 μm for aesthetic reasons. Right panel – Zoom-in of the optical and IR HST photometry.