Yep, same problem here. Android auto works, spotify sound works, but no voice feedback, only a crackling noise (like a machine gun firing) when voice feedback is supposed to be. Seems like no voice/system sounds work on android auto. It is a known problem and listed in the latest update on samsung members. Hope they will fix it soon.
Sorry to hear that you are having issues with Android Auto, Beta Testers. Please can you share your feedback on the Samsung Members App > Beta Feedback?
If you share a log when you are experiencing the issue (or within 15 mins), our developers can look into why this is happenining so we can improve this for the general release of OneUI 2.