Comparisons of the spectra of SN 2024acyl at different phases with those of the transitional Type IIb/Ibn event SN 2018gjx and several Type Ibn events with H signatures, such as SNe 2006jc, 2010al, 2011hw, 2020bqj, and PS1-12sk. Left panel: Spectra obtained at around the time of maximum light (∼10 − 20 days). Right panel: late-time spectra (∼50 − 120 days). The key spectral lines (H and He) are marked with coloured dashed lines. The phases marked on the right side of each spectrum are with respect to the epoch of their maximum light. Spectra with low S/N have been binned with 20 Å; the original (unbinned) spectra are displayed in lighter colours behind. All the phases marked in the figure are related to the (approximate) explosion epoch.