GLS periodograms of the ESPRESSO RVs, activity indices, and the observational window function. The RV and activity index values were median-subtracted for each dataset before (E18) and after (E19) the June–July 2019 intervention. Horizontal lines indicate the FAP levels at 10% (dash-dotted green line) and 1% (dashed orange line). The vertical dotted red line marks the orbital period of TOI-283 b (P = 17.61745 days), while the vertical dash-dotted gray line indicates the period of the long-term signal (P = 1356 days; see Sect. 5.4).