I am exactly the same, no cameras not flashlight, reset settings, no change, completely erased phone, restarted without recovery from backup, still nothing, restored from old backup, still nothing!
Initially my facetime camera worked, and the main camera only worked via the filmic app, but flash and main camera would not work via the apple camera icon, it was just black on screen. I updated to 17.5.1 tonight hoping the issue had been resolved but still the same, even after a reboot.
Apple support ran diagnostics on my phone, tried to tell me there is an issue with my camera (no sh*t Sherlock!) and since then, neither facetime or main camera work!! not even thru filmic app. so now I am left with no facial recognition too! this issue is 100% firmware related and do not let apple tell you otherwise!
apple's suggestion - Take it to local service centre! - I have told them I will not be paying for their poor firmware update causing problems with my phone. It is spotless, always in a case, never been dropped and worked perfectly until 17.5.0!! so frustrating.
I have an appointment at service centre tomorrow 23-05-2024 - I will let you all know the outcome of that.
Not impressed!