Spectral time series of SN 2020fkb redshift corrected to rest frame. The spectra have been corrected for both Galactic and estimated host galaxy extinctions, and vertically shifted and normalised for clarity. The epochs are provided respective to the estimated light curve maximum. The most prominent spectral features are labelled coming either from the host galaxy (blue) or from the SN (red). The Doppler shifted positions of the He I and Fe II lines are indicated with cyan vertical lines in early epochs as suggested by the velocity of the He Iλ5876 absorption minimum. The most prominent narrow host emission features are shown in grey, and the telluric band wavelengths with a circled plus sign (⊕). The spectra of SN 2020fkb likely contain some host continuum contamination at the blue end, in particular in the late epochs. Selected spectra of normal Type Ib SN 2004gq (Modjaz et al. 2014) are shown for comparison (green), and show very similar spectrophotometric evolution, but somewhat larger line velocities.