When accelerating, the sound quality of the sound will deteriorate when the playback is accelerated in Unity, and the diffusion of the sound image will diverge, like a spread effect .but this is not a must every time. FMOD Time Stretch in unity - YouTube
A lot of this can be down to the sample rate of the audio file you’re using.
A higher sample rate on an audio file allows you to change pitch with fewer artefacts at the cost of requiring more resources. Ensure your raw audio file is rendered at a high sample rate and match that setting the in the asset browser’s Advance Encoding Settings before building to a bank.
FFT size is the same result,I remove the pitch shifter,keep pitch in master channel.The spread effect will no longer appear,but it will be changed the pitch