Discord bug: I don't know why this has to be fixed by Nvidia, and NVidia is not making this update mechanism clear, but it would obviously need Geforce Experience installed, which I won't do.
Regardless, if like me you don't install Geforce Experience, all you need is the latest driver released today. In the notes for the driver release, it clearly states that it includes a fix for this (from page 13 of the PDF):
3.1 Fixed Issues in Version 528.49 WHQL
Adobe Bridge stability issues with 528.02 
Disable Hitman 3 Resizable Bar profile on Intel platforms 
Discord update causes GPU memory clocks to drop to P2 state 
- “So many people forget that the first country the Nazis invaded was their own." - Abraham Erskine, 'Captain America: The First Avenger'