When an Audio Sources Pitch or Volume is animated it causes the audio to pop and crack i found this when i created my VRC_Otamatone with av3 adjustable pitch. You can test it out with avtr_785db18b-3112-4680-a02e-b48e7e2b0b5b just use the avatar 3.0 menu and turn on the otamatone and use right fist gestures and with the trigger weight control its volume and in your left hand use the av3 note control radial menu.