Hi, I accidentally update my mi box to oreo 8.1 (previously 8.0). I use Nord VPN to access netflix and I'm aware that it doesn't work on Netflix v6 and only work on Netflix v5. Since I upgraded to Oreo 8.1 I could not downgrade my netflix to v5 becaause after the update it becomes v6 by default and is now the lowest version that I can downgrade to. I could not over-write it using manual installation from Netflix v5 apk files. Is there any way to downgrade my netflix app from v6 to v5?
I'm afraid you are out of luck.
None of the solutions offered here in the comments will work. Once you take the Oreo update, the new version of Netflix is installed as a system app and there is no way to uninstall or downgrade it. It's just how Android works.
I'm stuck in the same exact situation as you with NordVPN.