Bluetooth security aspect today after 'Blueborne' vulnerability?

[Decoman]

I was listening to Dave's video on the new bluetooth speakers, and I couldn't help but wonder for myself, yet again, what Bluetooth security is like. I tried figuring it out some time ago, but I was not able to.

The reason I ask this here, is that I don't understand the previous vulnerability (or maybe a set of vulnerabilities) called 'Blueborne'. Some known set of 2017 vulnerabilities related to Bluetooth I think. Said to have impacted maybe billions of unites unless I remember that part wrong.

https://en.wikipedia.org/wiki/BlueBorne_(security_vulnerability)

I asked in the Microsoft thread on Reddit not too long ago, but it looks like my thread was deleted for reasons unknown to me. Rules say things has to be "news" related *shrugs*. I simply asked what the status was for the now known Blueborn vulnerability.

So, what I am wondering is:
Where exactly is the damn vulnerability?
Is it in the standard somehow?
Is it in the hardware of headphones and anything else that connects via Bluetooth standard?
Is it the firmware of said hardware for headphones and the like?
Is it the drivers on say Windows machines, that uses an antenna to connect to Bluetooth units?
Is it related to Windows and Linux operating system?
Is it related to USB Bluetooth transmitter/receiver? Or its drivers, firmware or hardware?

As an owner of Sony's wireless headphones, I am bewildered as to what Bluetooh security is, and I find it disgusting to think about it.

Anyone have a clue about Bluetooth security after 'Blueborne'?