It's a common issue for games, but I trust it's fixable in Minecraft, as long as many of popular software I know have already found solution.
I didn't test for non-bluetooth sound devices, but I can assume this behavior applies to any of sound output devices.
If you open Minecraft without bluetooth speakers connected, then turn on bluetooth speakers, Minecraft won't automatically set sound output to the speakers, even though you set them as primary sound output device in Windows settings (I didn't test on Linux, Windows only).
Also, even if you launch Minecraft with speakers turned on, then switching them off, and then turning them on back again, Minecraft still won't produce any sounds until you restart the game.
Thank you for your report!
However, we are already tracking this issue, and this report is a Duplicate of MC-44055, which has been marked as Won't Fix - while this behaviour is not desirable, the developers have said that they will not or cannot fix it.
Please use the search function in the future to prevent duplicate reports.
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