Compatibility Report

• Name of the game with compatibility issues: Fallout: New Vegas
• Steam AppID of the game: 22380

System Information

• GPU: NVIDIA GeForce RTX 4080 SUPER
• Video driver version: 550.120
• Kernel version: 6.8.0-53-generic
• Link to full system information report: Gist
• Proton version: Experimental

I confirm:

• [x] that I haven't found an existing compatibility report for this game.
• [x] that I have checked whether there are updates for my system available.

Symptoms

Fallout New Vegas seems to have issues with the HDR effect (no sun glare and aggressive switching between brightness levels - eye adaptation) when running it via Proton Experimental or 9.0-4. Proton 8.0-5 does not have this issue.

Here are videos showcasing the described problem:
[Working] 8.0-5
[Broken] Experimental

The problem happens with or without mods (I have completely nuked my installation and re-downloaded the game to make sure)

Strangely, the same issue does not appear on my Steam Deck, regardless of the Proton version used. Maybe it's a problem with my PC's GPU or driver in conjunction with Proton?

Reproduction

1. Launch Fallout New Vegas with Proton Experimental
2. Look at the sky (it's more noticeable during sunsets and sunrises - the videos show early morning footage)