BuckWylde This is a known temporary issue.
Android 15 QPR1 introduced a bug requiring the Microphone (record audio) permission for routing local audio too. It impacts Android Auto on both GrapheneOS and stock OS, but only users on GrapheneOS will notice it because the permissions aren't granted by default.
https://grapheneos.social/@GrapheneOS/113629803646184979
Our next release will have a fix for this issue to avoid the audio recording permission (Microphone) being needed.
If you need this feature and don't use the voice features for Android Auto, you can choose if you want to work around it by temporarily granting it this access.