My wife uses Freestyle Libra and is not on the Android 13 Beta (She has a Samsung S21 FE) and her sound changed also but it was following an update to the Freestyle app. I guess the person you spoke to from Freestyle either doesn't use the app or isn't aware of the changes made by the app dev team
On my S10+ powered by Android 10 improved by One UI 2.0,
Ben Ginders