When an avatar with an audio source with an ONSPAudioSource component enters a VRC_Player Audio Override region with the default settings for avatar audio, the audio seems to become quieter. This should not happen, as the documentation states that these settings are the default that is applied when no VRC_Player Audio Override is in effect.
ONSPAudioSourceのあるアバター音源が、アバター音源設定がデフォルトのままのVRC_Player Audio Overrideに入ると、音が小さくなる。資料によると、このデフォルト値はどのVRC_Player Audio Overrideに入ってない状態と同じ値のはずなので、この現象はバグだと思われます。