Redshift, phase, and SALT2 x₁ distributions of the ZTF SN Ia sample. Left: Redshift distribution of the full ZTF SN Ia sample (grey dashed line, 2959 SNe Ia) with good light-curve coverage; the sample with a redshift limit at z ≤ 0.06 (blue dashed line, 1093 SNe Ia); and SNe Ia passing our other cuts that have a spectrum at −5 to 5 d with respect to maximum light (red solid line, 482 SNe Ia). Middle: Rest-frame phase distribution of all good light-curve coverage ZTF SNe Ia spectra at −5 to 5 d (grey) and with the redshift cut of z ≤ 0.06. Right: SALT2 x₁ distribution of the ZTF SN Ia sample.