Disabling driving can’t text message on my iPhone 11

Try setting DND while driving to manual.

"Customize features for Do Not Disturb While Driving

To customize how Do Not Disturb While Driving works, go to Settings, then tap Do Not Disturb.

Tap Activate to choose how you'd like Do Not Disturb While Driving to turn on.

• Automatically: Your iPhone uses information like motion detection and network connections to sense that you might be driving, and turns on the feature.2 3
• When Connected to Car Bluetooth: Do Not Disturb While Driving starts when your phone connects to the hands-free system in your car.3
• Manually: Use Control Center to turn on Do Not Disturb While Driving before you start.
• Activate with Carplay: This automatically enables Do Not Disturb While Driving while your iPhone is connected to CarPlay."

How to use Do Not Disturb While Driving - Apple Support

-AJ

Have you turned off the "Activate with CarPlay" option as well?