The forthcoming iOS 16.3 is now confirmed to fix an issue where some iPhone 14 Pro Max users were seeing one or many yellow lines at startup.
iOS 16.3 fixes the horizontal lines bug
As previously reported, the horizontal lines were appearing for an unknown number of users of the phone. Apple claimed that it was a software problem rather than a hardware one, and that now appears to be confirmed.
Apple's full release notes for the iOS 16.3 developer beta include the detail that it "fixes an issue where horizontal lines may temporarily appear while waking up iPhone 14 Pro Max."
The latest beta of iOS 16.3 is a Release Candidate one, and it's expected that the update will be released publicly in the week beginning January 23, 2023.
As well as the fix for the horizontal lines, the iOS 16.3 update will bring a new Unity wallpaper for Black History Month, and also introduce hardware security keys for protecting Apple IDs.