When iPhone is powered off SMS and iMessages go missing...

I turn my iPhone off at night and back on again the following morning. I appreciate it’s far from usual, but it’s always been my preference. Ten months ago, my iPhone stopped receiving SMS messages sent to me when it was switched off – now the same is happening with iMessages. I know I’ve been sent them as, when I press the power button to illuminate the locked screen, it says iMessage/SMS and then the number… but, when I unlock the phone, there are no new messages.

If it was just an SMS issue then I could see how it might be a carrier (Three Mobile) issue, but now iMessages, too?

I’ve had eleven years of continuous iPhone ownership: first a 5C that lasted seven years, and now my current SE 2020 that I’ve had for the past four years – up until November 2023 this was never, ever an issue.

I’ve spoken to Apple technical support on numerous occasions, but a solution evades me. Even the iOS 18 update hasn’t fixed it. I believe that, because practically nobody else turns their devices off, it’s not an issue that Apple has any interest in addressing. Still, I don’t think it’s too much to hope for when I’d expect even a Nokia 105 to retrieve text messages received when it’s been powered off.

*Politely: replying “Just don’t turn your iPhone off, then” is not in any way

useful to me*