Although this happens on my entire phone, my best example is Discord. On the left is what discord chat usually looks like, but when my phone bugs out, it changes to the color on the right. Does this happen to anyone else?
Thank you for posting in the Apple Support Communities. We're glad you reached out, and we'd like to offer our support.
For the issue of your display unexpectedly getting lighter, we suggest checking your brightness and color temperature settings. Here's how:
Adjust the brightness and color temperature on your iPhone, iPad, or iPod touch
Moreover, using Dark Mode can also change the display's appearance in low-light situations. More on that here:
Use Dark Mode on your iPhone, iPad, or iPod touch
We hope this information is useful. Kind regards.