Parasitic oscillations would tend to occur mostly in:

Parasitic oscillations are spontaneous, unwanted oscillations occurring at frequencies other than the amplifier's intended operating frequency. They tend to occur mostly in RF power output stages because these stages deal with high power levels, high gain, and stray reactive components like capacitance and inductance. The physical layout of high-power RF stages makes it easy for stray feedback paths to form, allowing output energy to loop back into the input. If this feedback is in phase, self-oscillation happens, which can damage equipment or cause severe out-of-band interference. Distractors like high gain audio stages or mixers generally operate at much lower frequencies or lower power levels, making them far less prone to sustaining damaging parasitic oscillations. High voltage rectifiers are power supply components and do not amplify signals at all.