Not to hijack this, but I have the same exact problem. I've attached my log file.
In there I noticed: NVIDIA DLSS not available on this hardward/platform., FeatureInitResult = 0x00000001, info: N
even though I have the a 4090 and the latest driver as of yesterday.
Here's the log file. Any hints you can give would be appreciated.
For system sanity sake, I checked MS Flight Sim and DLSS is available and on in that sim.
Bob
dcs.log