Comparison of the Hγ (top) and Hβ (bottom) line profile of the target AV-238 for three different observations (Dec. 2020, May 2021, and June 2021) and calibrated with three different FLUX standard stars (black: EG 21, blue: LTT 9789, red: GD 153). The residual plots show the ratio of data calibrated with LTT 7987 (blue) and GD 153 (red) and those calibrated with EG 21. The 1 and 2% inconsistencies in the blue wing of Hβ and Hγ, respectively, disappeared when using the new flux models. The remaining differences located in the core of the lines are likely of astrophysical origin (e.g., line profile or RV variations, or nebular correction residuals).