Stacking often reduces false color in stars rather than removing real color.

Two likely reasons were identified:

1. Single-pixel / Bayer sampling effects: stars can be so small that, in a single frame, much of a star falls on only one or a few sensor photosites. Because color cameras use a Bayer pattern, that can give a star an exaggerated red/green/blue tint depending on exact placement. When you stack many slightly shifted frames, those sampling errors average out, so the star looks less intensely colored.

2. Channel clipping / brightening: if stars are pushed brighter during stacking or editing, RGB channels can approach or hit their maximum values. Once channels clip, the ratios between R, G, and B compress, so color is lost and stars become more neutral or white.

So the stacked image is likely more accurate, and the stronger violet seen in single frames may be a sensor-sampling artifact rather than the star’s true color. To preserve genuine color, avoid over-brightening stars and watch for clipped channels during processing.