Branch spectroscopic classification scheme. SNe Ia classes are shown in various colours: SS, red; BL, blue; CL, green; and CN, orange. The dashed lines separate these regions (Phillips et al. 2022). SNe Ia in late-type (Riess et al. 2016, Cepheid calibrators) and early-type galaxies (Khetan et al. 2021, SBF calibrators) are shown as blue triangles and brown diamonds, respectively. SN 2020ue and SN 2020nlb are highlighted as black and red stars. Transitional and fast-declining SNe Ia, such as SN 1991bg, 1997cn, 2007on, 2011iv, and 2015bo, as well as early red events, such as 2018aoz and 2021aefx, are also included (Gall et al. 2018; Hoogendam et al. 2022; Ni et al. 2023a,b).