Bluetooth controllers actually do behave weirdly on the Deck, the polling rate is sub optimal. You can modify certain system files to help, but you’d have to reset the setting after every update.
But for audio, it’s mostly fine. I really do not have issues using this phone to Deck setup. You could consider a full system reset if it’s that bad on your end, it’s supposed to work well.
Double check if Secure Boot is disabled, xone and xpadneo have known issues with secure boot.