The Glare node shifts the color of the highlights when the threshold is
high. That's because the thresholding algorithm simply subtracts the
threshold from the RGB data, which is not expected to retain the same hue
of the color.
To fix this, we do the thresholding only on the luminance of the color
in HSV color space. This eliminates the color shifting and also helps to
smooth the edges of the highlights.
This is a breaking change, but it is more of a fix rather than a change
of behavior.
Pull Request: https://projects.blender.org/blender/blender/pulls/122570
4f21b26675