Check if PulseAudio has any active modules related to Bluetooth
pacmd dump | grep module-bluetooth
PulseAudio usually has 2 modules loaded by default
module-bluetooth-policy and module-bluetooth-discover
to disable the modules, use this command to add comment tags to the configuration file
sudo sed -Ei '/load-module module-bluetooth*/s/^/#/' /etc/pulse/default.pa
then reboot or restart system, or use this command to restart PulseAudio
systemctl --user restart pulseaudio