Time stretching using FMOD_DSP_PITCHSHIFT_PITCH and setFrequency make the sound unclear and its volume lower

I used FMOD_DSP_PITCHSHIFT_PITCH and set frequency together to lower speed of the song without changing pitch.
if I don’t use FMOD_DSP_PITCHSHIFT_PITCH the sound is clear, but when use FMOD_DSP_PITCHSHIFT_PITCH the sound becomes unclear
Also I used dsp Info and saw that the vu meter shows lower values when FMOD_DSP_PITCHSHIFT_PITCH is used.
How is that and how I can overcome this issue?

Have you tried increasing FMOD_DSP_PITCHSHIFT_FFTSIZE above the default to reduce “smearing,” as described in the FMOD-DSP_PITCHSHIFT documentation?

What’s the sample rate of the audio file you’re lowering the play speed of?

Yes, I have set it to 4096, better quality longer delay but still lower volume
sample rate is 44100