I know CCD scans the array line by line and over voltage from even a single pixel can wreck the whole line.
But why are these wrecked lines colored magenta?
White light suitably similar to sunlight (and even most artificial light sources try approximating it to some degree) has its maximum intensity in the green part of the color spectrum so the green sensors max out at lower brightness of white than the red and blue sensors. Interpreting all sensors as delivering the same value for that reason leads to a color that is significantly tinged magenta in a white balance setting similar to sunlight. Different white balance settings will lead to a different hue of the maxed-out bands but it would be unusual not to lean in a magentaish direction without additional processing.