Hey, I am sorry to learn about the sound issue of your Liberty 3 Pro. May I know how does it work now? Was the issue fixed?
In case the issue still persists, may I know what is the firmware version of you upgraded to? 4.58 or 4.69? You could try to troubleshoot the issue by placing the earbuds back into the charging case, and closing the case for about 6 seconds, then taking them out and testing it again to see if it helps at all.
If it doesn’t work, please drop an email to "service@soundcore.com" by detailing the issue and the order#, our Soundcore technical support will take care of your case and make this thing right as soon as possible.