I can confirm the color change, but if you change the pantone color to RGB it will display as seen in your first screenshot.
There are problems with color management in the share for review feature.
It does not surprise me that a Pantone color (which is actually a mixed printing ink) that may not be able to be created with sRGB or CMYK colors is not displaying properly in an online version of the document. Overprint Preview gives the best preview of a pantone (Lab) color, but that is not supported in Share for Review.