Reliable 110 & 230V AC line detection on 3.3V GPIO
I basically need a circuit that detects 110 &amp; 230V AC, but ignores the
induced voltages from coupling.

Your circuit is far too sensitive for just detecting the presence of mains voltage. Reduce the value of R19 until it just manages to detect the lowest AC voltage you want, eg. 90 VAC. With the MMBT2222A a value of 2.2 kΩ should work.
I don't recommend using a FET because the Gate threshold voltage is not very precise.
With R19 = 2.2k this circuit should handle induced current of up to ~150 uA rms, which corresponds to ~2 nF of capacitive coupling at 240 VAC 50 Hz. If you still get false detection then you may have to add a load to shunt way the 'leakage' current. A 0.1 uF capacitor would allow up to ~30 nF of capacitive coupling, but it would have to be mains rated and therefore quite bulky.