Multiple active exploits could affect iPhone use of Bluetooth.
Flipper Zero hacker tool could be used to trigger iPhone DDoS attack using Bluetooth signals by AirPods, HomeKit accessories, etc. These signals usually trigger popup on iPhone allowing to connect to headphones or perform other actions. Crafting these signals in a specific way could result in iOS restart.
Newly discovered BLUFFS attack could be used to impersonate devices and trigger disclosure of private information. It is not yet clear, if AirDrop is affected by this attack as it uses more than just Bluetooth to authenticate the device. However, it is still possible to hijack audio or other Bluetooth connection. Fix would require device manufacturers to modify security mechanisms of Bluetooth stack.