Hello jlhupz,
Thanks for reaching out to the Apple Support Communities. I can see from your post that your Bluetooth is not turning back on when you turn it off from the Control Center. When you turn it off from the Control Center, it will not disconnect from Apple Music, Instant Hotspot, Apple Pencil, and Continuity features, like Handoff. It will disconnect from other accessories. You are correct, according to the article, “Use Bluetooth and Wi-Fi in Control Center with iOS 11 and later,” your Bluetooth should turn on after 5 AM local time. Use Bluetooth and Wi-Fi in Control Center with iOS 11 and later - Apple Support.
You mentioned that your iPhone is running the latest iOS, have you tried any other troubleshooting steps, such as restarting your iPhone as shown in this article: Restart your iPhone, iPad, or iPod touch? If you could provide some additional information it may help someone get you to a solution. Try answering the following questions:
1 - When did you first notice the Bluetooth not turning back on?
2 - Did you have any issues with the Bluetooth not turning back on before iOS 12.1.3?
3 - If you turn off the Wi-Fi from the Control Center, is it turning back on at 5 AM local time?
4 - What Bluetooth devices are you expecting to reconnect with in the morning?
Enjoy your day!