Steps I followed-
1. Did USB port mapping (Just to be on the safe side since some users reported issues with the USB)
2. Updated OpenCore to 0.6.8 yesterday (Config.plist>Kernel>Quirks>XhciPortLimit=False)
3. Updated all kexts to the latest version
4. Kept a backup of EFI
5. Checked here before updating if other users were having any issues.
6. The whole update process took about 90 minutes for me.
7. All USB ports are working fine.
I had problems with USB after updating. I updated to the latest OpenCore and updated all kexts before updating.
Initially, I assumed it was a mapping problem, but then as I was remapping with USBMap I realised they were all working fine with my external USB drive. Through trial and error I realised my external drive and USB Ethernet both worked fine, my microphone and iPhone wouldn't work at all, and my external sound card was flashing but not working. I searched for the error message flashing from my sound card and found it referred to a lack of power from the USB source.
I then added the SSDT-USBX referred to here (no idea why it worked before now without this), and a reboot later, it worked. So it looks like it wasn't a USB Mapping issue per se, but a USB power issue. Hope this helps someone.