Controlled impedance in presence of vias and through-hole components (PTHs)
Trace characteristic impedance, that of either microstrips or stripline, is determined taking into account the PCB stackup/geometry without vias. At 3x the calculated required trace width nearly all (e-3) of the original signal will have dissipated.

The signal return path is important for high-speed currents. At high frequencies current follows the path of least inductance, not least resistance, which is normally whichever path is closest to the signal trace. Return current density falls off inversely with 1+(D/H)2, at a point D units away from the signal trace on a return layer H units thick[1].

So, one needs to pay attention to the D/H ratio in addition to trace width W: stay 3xW and 4xH away from the trace (4.36xH.. for 95% dissipation).

[1] See eq. 5.1, pg. 190, of High-Speed Digital Design by H. Johnson, M. Graham.