Spectral comparison at a similar phase (around 1.5 months after the V-band maximum) of SN 2021foa, Type IId SNe 2013gc and 1996al, SN 2009ip and the 2009ip-like event AT 2016jbu, the prototypical Type Ibn SN 2006jc, and the transitional Type Ibn/IIn SNe 2005la and 2011hw. Different colours indicate different SN types: SN 2009ip-like in blue, SNe IId in red, transitional IIn/Ibn in green, and Ibn in purple.