TOI-3884 b in context. Left: planetary vs. stellar radius. Black dots are transiting planets listed in the NASA Exoplanet Archive (https://exoplanetarchive.ipac.caltech.edu/ with a planetary radius uncertainty smaller than 20%. The blue circle with error bars marks the position of TOI-3884 b. The histogram of known planets is shown at the right of the panel. Centre: planet radius vs. insolation flux. Error bars mark the position of TOI-3884 b (blue) and grey dots are planets listed in the NASA Exoplanet Archive with a radius uncertainty smaller than 20%. Right: transmission spectroscopy metric for planets with a radius between 1 and 10 R_E. Data are taken from the NASA Exoplanet Archive. Grey areas are below the cutoffs that Kempton et al. (2018) suggested for follow-up efforts. The symbol with error bars is TOI-3884 b. The colour indicates the equilibrium temperature of the planet, computed for zero albedo and full day-night heat redistribution.