She's had a lot cold night before I got her s...

She will already looking good just let her adjust to the new environment and she will be looking lovely again

Thats a beautiful plant, great job bro.

Would try to carefully give her some more nutes and always water till runoff and maybe check the ec of the runoff just to rule out nute lockout but I doubt its that. Mine looked like that too and it was just an early fade which i guess is the most likely scenario

Shes hungry. My number 1 flower tip and I repeat it often on here. You still need a grow formula or a normal amount of nitrogen for the first 3 weeks after you switch to 12/12. Your plants need this for the stretch and they don't just automatically switch over because you switched the light schedule. Weeks 4-5 your plant will need cal mag to produce buds. Calcium is the plant cell wall building block. This will help with the early fading and the dark or purple stems. Best of luck. Your plants look like they did fairly well. Mostly just an early fade. Good job