Test page: https://woerndl.github.io/nightshift-test/
Noticed this right away on my iPhone 18 Pro. With Night Shift on, for example, photos containing egg yolk or other orange items clearly turn pink, and other saturated red and orange tones go pink or salmon too. My old iPhone 15 Pro, also on iOS 27 with Night Shift at More Warm, doesn't show the pink shift.
I made a test page so you can try it yourself:
- Set the Color Temperature slider to More Warm (Settings › Display & Brightness › Night Shift).
- Open the test page and toggle Night Shift on and off in Control Center while looking at the grid.
It's strongest in the P3 S100 row and also clear in sRGB S100. Screenshots won't show Night Shift. To capture it, take a photo, ideally with a second device in the same shot.
If you can reproduce it, please file a report at https://feedbackassistant.apple.com/ (there's copyable text on the page) and open an issue here with your device, iOS build and whether True Tone is on. The more reports, the better the chance Apple actually fixes it. My report is FB25121206, feel free to reference it.
Also discussed in this Reddit thread and on MacRumors.