The Apple Root CA I see right now expires Feb 9, 2035. If that's the one you mean, it looks updated now.

I found this other forum thread which might be relevant. https://developer.apple.com/forums/thread/774009?answerId=824326022#824326022

Or maybe just contact AppleCare with your proof of purchase.

Is it possible you could have bought a stolen phone? Or perhaps your serial number was transposed somewhere? Perhaps if you post your serial number someone at Apple can look it up.