Hi OrKurtz,
Thank you for reaching Microsoft Community. I'm sorry to hear about the issue you encountered after the firmware update on your Surface Headphones 2.
Surface Headphones 2 should still support aptx codec. Please try these steps below to troubleshoot then see if these helps:
1: Turn of then on your Surface Headphones
2: Restart the host host device
3: Disconnect and reconnect the headphones
4: Check if an update is available on the Surface Audio app
For Windows: see Get updates for apps and games in Microsoft Store
For Android: see the Google Play Store
5: Uninstall and reinstall the Surface Audio app
6: Reset the firmware of your Surface Headphones 2
See: Reset Surface Headphones (microsoft.com)
Hope this helps.
Kind regards,
Marrion