Hello Lemmings_Leap,
Thank you for reaching out in Apple Support Communities. We understand that only a few images and not all images, are displaying reverse colors on the display of your iPhone. We'll be happy to help.
Based on the screenshots you provided, it seems that Classic Invert is turned on. You mentioned trying Smart Invert and Classic Invert on your iPhone. To confirm, do you have Classic Invert on or off? We suggest to review if, Classic Invert is turned on by going to Settings > Accessibility > Display & Text Size.
If this feature is already turned on, you can temporarily turn this feature off and restart your iPhone. From there, you can toggle, "Classic Invert" on and see if all the images are displayed in reverse colors. That's if, this is the feature you would like to keep on. Here's more information about the accessibility features on an iPhone: Adjust the display and text size on iPhone
We look forward to hearing back from you with an update.
Kind regards.