Thanks for posting and welcome to the Bose Community. I am deeply sorry to hear that you have encountered some audio issues with your Soundbar 500 and would love to assist you further.
Can you please confirm if this issue happens across all sources as well as if you hear muffle sound when Bluetooth to the system? Firstly, I would recommend that you perform a reset on the Soundbar via:
Turn the soundbar off
Unplug the soundbar power cord from the power outlet
Wait 30 seconds
Reconnect the power cord
Wait 30 seconds for the system to reboot
I look forward to hearing back from you regarding the result of this and if any other community users are also experiencing this issue please do let us know.