More of an outfit change than anything, Rachel's character as a whole has not changed. The change comes from the fact that she was strutting her stuff just like a certain Princess, and I felt it necessary to discontinue that... by simply adding jean shorts and a white t-shirt to her existing uniform. Easy enough.
Note: v2.0 is just as canon as v2.5. Background is the Knothole map WIP for the TSAT game.