Nobody can explain to me so far

[RoseSD]

Why did the rebloom of this lovely purple orchid turn into a spotted pink with a different shape? I did use a cytokine paste to encourage birth at the nodes, but no report of "mutant flower" was made as far as I know.

[camille1585]

This is a topic which pops up regularily on the forum, and sometimes the change in color is so extreme that people have a lot of trouble believing that there isn't a plant mix up or a prank involved.

That being said, it's known that temperature and light can radically change the color of a bloom. Here is an example of this with a Oncidium hybrid: Two different colored flower spikes on same Phal?

Another possibility is a genetic mutation, as you mention, and since you used keiki paste, I'd say that it is a very plausible explanation. The messed up shape of the bloom is also a good indication that some unwanted mutations occured.

It also appears that the color of these harlequin Phals may not always be stable as color change is something that seems to happen pretty frequently in this type of Phal. In this thread Two different colored flower spikes on same Phal? someone posted that in Phal Magic Art for instance, the color is not stable and it can sometimes revert to bloom in the 'normal' color.

Here are some other examples of color changing harlequin Phals:
Harlequin Dtps. Jiuhbao Fairy
Two Different flower in one spike of Phal

[SG in CR]

What Camille wrote makes a lot of sense. The one other thing that I could think of is that I've seen Phals with obvious artificial coloring. My sister showed me a crazy looking blue and purple one that her kids picked out for her Mother's Day present and I told her I'd expect all the blue areas to be white next time it blooms. Could it be that someone is dyeing Phals with more natural colors like the purple in the initial bloom? If so, then I could imagine that reblooms would end up colored something like in the second photo.

[Ray]

The impact of the hormone treatment may not be genetic, but it still the likely factor in the deformation.

If you get a plant from that node, once it is no longer receiving an overdose of hormones, the flower shape should rectify.

[Fairorchids]

The primary color difference, is a significant reduction in anthocyanins.

This pigment class is known to be heavily influenced by:

1. Temperature
2. Light
3. pH (which determines red/blue hue)

[SouthPark]

Just referring to the thread title ----- "nobody can explain to me so far"

Was there a particular forum - somewhere - where your question was asked, and was discussed?

[RoseSD]

Not here.
Facebook.