This is what's happening to me on my iPhone 13 on iOS 15.5. All settings on the device is set to default except that I have Keyboard Auto Correct switched off, and that I have disabled the 24 hour time format in Date & Time settings. I have reinstalled the latest version of iOS 15.5 through a Mac using the DFU method... That did not help. I really like this iPhone, please fix your software Apple! This flickering pink screen; it's not very convenient! I have tried to see if it will go away if I take off the case, nope didn't help. I tried to disable Auto Brightness, True Tone, Tap to Wake, Raise to wake; nope, didn't help! I spoke to Apple Support, they ran a diagnosis and they couldn't find ANY hardware issue whatsoever. This is MOST definitely a Software Bug/Issue in iOS 15.4.1 & iOS 15.5!
[Edited by Moderator]