screen flickering in grayscale image

What are the factors causing screen flickering in grayscale images on LCD displays?  

Answer: Main reasons; A. Unstable driving voltage, VCOM voltage drift, mismatch between the TFT common electrode voltage (VCOM) and pixel voltage (Pixel Voltage), leading to unstable electric fields during mid-gray levels. B. TFT switch leakage current, excessive off-state leakage current (Off-State Leakage) in TFT transistors when turned off, resulting in a decline in pixel voltage holding ratio (Voltage Holding Ratio, VHR) (requirement >90%).