I wish Apple did a little more user training as to _what_ this means instead of a generic "let app use bluetooth?"
For certain permissions (i.e. location), Apple actually does require apps to provide a string indicating what the permission is needed for. I'm not sure if it's required for the Bluetooth permission, but my guess is that since it's a beta nobody has updated their binaries to include that string.
Is the string in practice any more useful than update messages? (I wonder sometimes if anyone feels shame over 20 consecutive fixes with public-facing summary saying just "Stability and bug fixes." Apple itself is, of course, far from exempt.)
It's not at all clear from the message it gives you, but I was worried about that too so I read the docs. It turns out the warning does not apply to anything trying to use bluetooth audio, because that goes through the audio API. So technically no app has access to your bluetooth headphones, they only have access to your audio subsystem which then accesses your audio device, bluetooth or otherwise.