JWST transmission spectra of TOI-270 d presented by B24 (red errorbars) and those used for our canonical retrievals (blue errorbars), combining NIRSpec data by HM24 with the NIRISS observation reduced in this work. Also shown are the 1-σ contours of the retrieved spectral fits to either dataset. The orange contours correspond to the retrieved spectral fit to the red errorbars using an equivalent atmospheric model to the free chemistry retrievals of B24, as discussed in Section 4. The turquoise contours correspond to the spectral fit to the blue errorbars using our canonical model, as discussed in Section 5. The present (blue) NIRISS data has been vertically offset by +28 ppm, the median offset retrieved for our canonical model, as with Figure 3. C25 in the figure caption refers to the data and canonical model presented in this work.