The Lens Distort node is different between CPU and GPU when jitter is
enabled. That's because GPU incorrectly assumed that jitter with no
dispersion would have no effect. So we fix this by adjusting the
identity condition.
Further more, the green channel was not jittered for the GPU, that's
because the jitter was only seeded by the integration steps and was thus
constant for all channels. And since the green channel is the result of
addition of two opposite accumulations, the green channel was left
unaltered. To fix this, we include the start channel of the integration
in the seed to the jitter to make sure different channels get different
jitter.
Pull Request: https://projects.blender.org/blender/blender/pulls/126993
bb87690549