When I owned my Note 10 Plus I bought an adapter, USB C to headphone jack from Samsung, so I could continue to use my Bose wired ear buds. It worked just fine.
I'm wondering if your external USB C plug is the source of the issue.
Whenever I encounter a problem I try to eliminate what works and what doesn't.
@AlexyN9, let's try some basics to see if we can move forward with this.
1. Restart your phone - a classic trick but also often incredibly effective. It also may trigger an available update to your phone
2. Check you're on the latest SW by heading to Settings > Software Update > Download now
3. Make sure all of your apps are up to date in the Play Store and Galaxy apps, remembering that even if you have your phone to download updates automatically if an app's permissions change that you will have to manually accept the update.
4. Test your phone in Safe mode, this will allow you to see whether a native or third-party app is causing this behaviour.
To access Safe Mode, press and hold the Power button until the 'Power off' prompt appears on the screen then release > Touch and hold Power off until the 'Safe mode' prompt appears then release > To confirm, tap Safe mode > With Safe Mode enabled, ensure Airplane Mode is turned off.
- If the symptom continues when in Safe Mode. Please use Samsung Members app to submit an Error Report to us.
- If the symptom stops when testing in Safe Mode, this is an indication that a third party application is interfering with this feature and you should review the apps you have downloaded.