Because I had AppleCare coverage on my iPhone, I called support on May 20th and spent 45 minutes on a call with a senior support advisor. She ran another remote diagnostic on my iPhone which showed no hardware defects of any kind, even though the front camera problem and the color artifacts in my photos were constant. She recommended that I just replace my phone with a new 14 Plus. I did that (my new phone arrived on May 23). I updated the new iPhone to iOS 17.5.1 and then transferred all apps and data to the new phone (the front camera on the new phone worked perfectly from the start and was not affected by the software update).
Then, on a whim, and before wiping all data from my old iPhone 14 Plus (which I had purchased new in late Nov. 2023), I accepted the prompt and updated by old iPhone to iOS 17.5.1. That software update instantly cured my front camera problem and the photo artifacts problem.
There has been a lot of media coverage about how iOS 17.5.1 has cured the problem of "deleted" photos being resurrected on users' phones. I have seen no publicity at all about how 17.5.1 also cures the "black screen" front camera problem, at least on some iPhones.
If 17.5.1 was released within the last couple of days, the Apple software engineers must have been working on this release for a while. The $64,000 question is: Why didn't the software engineers inform front-line Apple support personnel (on the hardware side) about how 17.5.1 was going to fix the front camera and photo artifacts problem? I could have saved myself several hours of time this week by just waiting for and installing iOS 17.5.1, without replacing my phone.