IRX–M_⋆ diagram of our galaxies compared to previously determined relations at different redshifts. Blue and red points show individual FIR continuum detections at 4 <  z <  5 and at 5 <  z <  6, respectively. Open downward triangles show 3σ upper limits of individual IR nondetections. Stacks are shown rectangles (blue at z ∼ 4.5, red for z ∼ 5.5). The nondetection of the stack is indicated by a downward arrow. The inset shows the median uncertainty of individual M_⋆ estimations (log (ΔM_⋆/M_⊙) = ± 0.34). Lines show IRX–M_⋆ relations derived in previous studies at z ∼ 2 − 4 (Álvarez-Márquez et al. 2016; Bouwens et al. 2016; Koprowski et al. 2018; Fudamoto et al. 2020). The gray band shows the 1σ uncertainty of the Fudamoto et al. (2020) relation. With the exception of the high mass bin at z ∼ 5.5, the population average stacked IRX values are consistent with this relation. However, the intrinsic dispersion from galaxy to galaxy at fixed stellar mass is clearly extremely large.