How do I fix Bluetooth not connecting automatically on iPhone 15 with iOS 18.5?

Recently my Bluetooth on my iPhone 15 (IOS 18.5) has stopped connecting automatically. Even my air pods do not connect automatically when I put them in my ears. It used to be that I could turn on my Bluetooth speaker and it would automatically connect to my phone but no longer. I am struggling to connect to car play. I have rebooted my phone. I have to go into settings to select the device from he Bluetooth menu each time now. Once I have done that the device works perfectly (except car play which is a struggle to get connected).

[Re-Titled by Moderator]

Original Title: Bluetooth no longer connecting automatically IOS 18