Override built-in components with an empty / "no-op" component to disable them.
The Bluetooth Proxy functionality doesn't (yet) allow for discovery to be disabled.
It seems one of our neighbours owns a nearly infinite amount of Oral B Bluetooth toothbrushes (or somehow keeps resetting theirs) and quite some LED BLE compatible light bulbs.
As we have neither, and I was getting fed up having to ignore a newly discored device nearly daily, both extensions are "disabled":