Top panel: power spectral density (in black) and background model fit using DIAMONDS for EK Eri from the eight-night observation run in 2017. The red line shows the total fit including the oscillation power excess, and the dashed blue line below the oscillation hump represents the flat-noise component. The inset shows the same spectrum, but in a log-log scale to help visualize the hump that is caused by oscillations, which is also marked by a red arrow at ν_max. A smoothing by 4Δν, with Δν derived from Stello et al. (2009) using ν_max from our analysis (solid green line), is also shown. Bottom panel: similar to the top panel, but here using the second observation run in 2018. The position of ν_max from the 2017 time-series is indicated by the red arrows, showing that there is no region where significant power excess is found.