What causes motor failure and sine-wave distortion?

As shown in Fig. 1, the IC creates an FG signal based on the zero-cross of the Hall input.
The half-period time of the FG signal is taken as the time for a 60° electrical angle, and the modulated waveform for the next 60° electrical angle period is generated.

If there is noise in the Hall signal, chattering may occur near the zero-cross, which will also cause the FG signal to chatter.
The IC will output a modulated waveform with a high frequency due to the chattering of the FG signal.
This fast modulated waveform will continue until the next Hall zero-cross, which can cause motor malfunctions and distortion in the current waveform. Please take measures such as adding a noise filter to the Hall input to cancel the noise.