Panels a–c: difference in mode frequencies of radial orders n_pg ∈ [ − 50, −1] of 3.25 M_⊙ models between the given mixing prescriptions: diffusive Gumbel (DG), diffusive exponential (DE), convective Gumbel (CG), and extended convective penetration (ECP). The horizontal lines delineate coloured regions that correspond to the Rayleigh limits of light curves of different lengths: solid line and grey area indicate 90-day-long data (K2), the dash-dotted line and yellow area indicate one-year-long light curves (TESS) and the dashed line and green area indicate four-year-long light curves (Kepler). The vertical dashed lines indicate the modes with n_pg = −10, −20, and −50 from left to right. The inset shows a zoomed version. Panel d: evolution of the frequency differences of certain modes along the main sequence evolution at various core hydrogen fractions.