Extrapolated rest-frame 144 MHz luminosities of 67 quasars in the parent sample with known redshifts and radio measurements that have not been confirmed as jetted from high angular-resolution radio imaging at mas-scales. Quasars with radio emission that is dominated by star formation are shown in green; those with an undetermined radio emission mechanism are shown in blue. The quasars in this work are shown in purple. The orange line shows a 3σ surface brightness threshold in luminosity for an unresolved point source detected in LoTSS, assuming a median rms noise of 0.07 mJy beam⁻¹. The SFR implied from the 1.4 GHz luminosity is shown on the right-hand y-axis using the radio–infrared correlation of Ivison et al. (2010). Most of the upper limits are from FIRST at the 5σ level, thus the LoTSS threshold shows a clear advantage in sensitivity.