HUGE difference between rendered view tab and actual render, Completely different from 2.90.1. Why?

WHy is this happening?

I should be seeing a grainier version of this

I have played with the various setting nothing makes difference except turn on or off ambient occusion render pass, which makes all colours light emitter.

Also, Open image denoise and optix denoise look like crap all of sudden when they work fine before. I had to adjust samples upto 1024 when before 512 was razor sharp and clean. Has anyone else had these problems? How do I fix this, short of rolling back to s.90.1, especially rendered view not working right.

Are you, by chance, using an AMD graphics card with recent drivers? If so, rolling the drivers back to a version before 20.11.2 might help. Apparently there’s some problem on AMD’s side.

Nvidia GTX 1080 8GB GPU. MSI Motherboard with an AMD Octocore processor.

The problem did not exist before I installed the current release of Blender 2.91. Good to know about AMD GPUs though!