Upper panel: weighted mean of the spectra of HD 36546, obtained on 13 Jan 2023, around the Ca II K line (blue), and the spline fitting the photospheric profile of the weighted mean spectrum built from all the available observations (red dashed line). The vertical grey dashed line marks the radial velocity of the star. Lower panel: ratio between the weighted mean spectrum from that date and the spline. The two vertical orange dashed lines mark the limits of the interval where the non-photospheric absorption is detected.