Redshift ~2.7 is not special

TL;DR

The paper argues that the previously reported galaxy spectral change at redshift ~2.7 is due to a data outlier and not a genuine cosmic transition, emphasizing the importance of data quality.

Contribution

It critically re-evaluates prior findings by identifying the influence of a single outlier, showing the original result was not statistically robust.

Findings

The spectral change at z~2.7 disappears after removing the outlier.

The outlier was caused by a questionable redshift estimate.

The original significance was an artefact of anomalous data.

Abstract

Galikyan et al. (2025) reported a statistically significant change in galaxy spectral properties at redshift $z$ $\simeq$ 2.7 based on a Kolmogorov Stochasticity Parameter analysis of JWST spectroscopic data of galaxies. In this comment, we demonstrate that their result is critically driven by a single outlier in the dataset. This outlier arises from the use of a questionable redshift estimate for one spectrum. When the outlier is removed or the redshift is corrected, the claimed transition at $z$ $\simeq$ 2.7 disappears entirely. By independently reproducing their analysis, we demonstrate that the claimed feature is not a robust statistical signal, but an artefact of this anomalous data point.