Bayesian analysis of variance (BANOVA), implemented through R packages, offers a Bayesian approach to analyzing experimental data. A tutorial in Psychological Methods extensively documents BANOVA. This note critically examines a method for evaluating mediation using partial eta-squared as an effect size measure within the BANOVA framework. We first identify an error in the formula for partial eta-squared and propose a corrected version. Subsequently, we discuss limitations in the interpretability of this effect size measure, drawing on previous research, and argue for its potential unsuitability in assessing indirect effects in mediation analysis. (PsycInfo Database Record (c) 2024 APA, all rights reserved).