HD 191939 b’s transmission spectrum observed with HST/WFC3 and reduced with independent reduction pipelines considering all visits and a model spectrum assuming no aerosols in the atmosphere and solar metallicity (see Section 3.1). Colored markers with error bars show the light-curve fits’ median values and 1σ uncertainties, and colored dotted lines depict the data’s weighted averages. A small offset in wavelength was subtracted from the data from the PACMAN reduction for visual clarity so that they do not overlap with the Eureka! data points. Magenta circles present the model spectrum binned to the wavelength channels of the PACMAN and Eureka! reductions. The ﹩{\chi }_{\nu }^{2}﹩ values given in the legend were calculated with each dataset and the clear solar-metallicity model.