I hit a similar issue with a UE5 game.
I found (using nvtop) that it was using my integrated GPU (from my Ryzen 7000 processor) which is so slow my system lagged really bad (mouse cursor moved at about 1 fps on the desktop after tabbing out of the game).
The solution I found was to select a different graphics back end. UE5 games take some command line arguments (documented here https://dev.epicgames.com/documentation/en-us/unreal-engine/command-line-arguments-in-unreal-engine ) which can select the graphics back end to use. I believe it was defaulting to DirectX12, and setting the launch command to %command% -vulkan fixed the issue.
My guess is that vulkan better enumerates the GPU devices, while DirectX12 does something which results in the game picking the wrong one.
My system is full AMD (AMD integrated GPU, AMD discrete GPU), so the issue is not intel specific.
I've written software for my own system that had this exact same bug in the past: GPU enumeration order can be quite fussy and backed specific, so it shouldn't be too surprising to see bugs like this, and swapping back-ends working around the issue. Definitely should be fixed though!
Replying to https://github.com/ValveSoftware/Proton/issues/7892#issuecomment-2292896441
Palworld has disabled vulkan support and I'm unable to launch it with vulkan altough I already tried vulkan dx11 dx12 and etc. I think actual problem is proton's compability with Nvidia GPU. While developing the Proton the first place they look is hardware for steam deck
Compatibility Report
System Information
I confirm:
Symptoms Unreal Engine Games are not running on discerete GPU even with prime-run or proton options. FPS is around 15 and GPU usage is 0. FPS is fine on menus tough. I researched about that and what I see is there is nobody can play Unreal Engine 5 games on linux laptops you can also see that in protondb. All of the users with intel laptop cpus had this problem