I was just able to solve an issue where WoW started flickering, and nothing on my system had changed at all.
Tried things like
- DDU in safe mode then reinstalling newest driver
- Renaming interface and WTF folders to .old (then running the game and quitting and moving them back)
None of them worked.
What finally worked was changing nVidia control panel WoW game profile (had to create one), Global profile both to fixed refresh instead of gsync.
I also changed my monitor from OSD to use fixed refresh instead of Adaptive sync (or gsync).
I ran the game this way and had no flickering.
Quit the game and then set everything back to gsync and ran the game again, and flickering was gone.
No game settings were changed at all.
I just wanted to leave this here for myself incase I run into it again, and also to help others so they dont freak out when their game starts flickering suddenly for no reason.