I would like to confirm that Bluetooth audio is unaffected by the issue that I documented here and here of this post.
This makes me think that the issue has something to do with the hardware and possibly firmware of the Librem 14 built-in speakers and headphone jack. But the issue only presents itself when using sys-audio, which I do not understand.
The good news is that I only need to start my sys-audio qube once if I only intend to use Bluetooth audio, while allowing me the option to enable the built-in speakers later by restarting sys-audio twice.