doesn't seem to be affected by the steam overlay although i did open #541 with a similar but not identical issue. this issue has more relevant and up to date information as well as a much more concise description of the issue. however that issue also has some information possibly relating to this issue as well.

same issue with both a 1660 ti and 3060 ti graphics card.

Ive got a solution.

Go to NVIDIA setting, switch Powerstettings to performance, default should be adaptive.
After this you need to delete your vrsettings file, because its stores the power settings.
Start Steamvr again, its recreate the settingsfile this time with the correct power settings.

I guess it will work for AMD cards too.

Async reprojection works fine in the current stable build of steamvr, the beta version (1.25.1) is broken.
Stay on stable and you dont need to disable async repojection.
With this its works like the Windows build!

// PS: I hope valves devs read this:
I would prefer not to switch to perfomance mode, but if you start from adaptive its creates 4 gpu speed states,
it seems that this states are not correctly read out from the driver.
I guess they should be equal to nvidias 4 states, but they are not.
All 4 states are kind of equal they differ around +- 10Hz which is not much different and the major problem,
they are around half of the speed of my max rate:

I use 3060ti, in adaptive in the settings file 4 values around 1100mhz are stored.
If i switch to performance, the values are not rewritten, thats the reason why i need to clear the settings file.
After the file is recreated it has only one value gpu0 with 2130mhz.
In my opinion thats the reason why the most linux users run in thouse major performance problems.

Switching back to adaptive seems to be recogniced by the settingsfiles, its restores the 4 states with the incorred values.
Please fix this.

where is the vrsettings file? also nvidia x server settings (nvidia-settings) seems to reset the power mode every time i restart my pc

The file is here: ~/.steam/steam/config/steamvr.vrsettings
In my case its doesnt, but i switch to adaptive after each round to conserve energy.
I dont want my gpu on full throttle if its not needed.

The way you initialize your windowmanger my not load the nvidia-settings config, that could be handled quite differently.

DE: KDE Plasma 5.26.4
WM: KWin (X11)

not sure what would be causing it to reset my power settings. I don't mind it being on all the time but it's a pain to have to keep changing it. Although i should only have to change it once for the vrsettings file to be updated right?

For more infos look at: https://unix.stackexchange.com/questions/46474/how-to-make-changes-in-nvidia-settings-tool-persistent
As i wrote if you switch to adaptive the vrsettings file updates the gpu values with the wrong ones, switching to performance is not working correctly, i delete the settingsfile everytime i switch to perfomance mode and start steamvr.
I know its uncomfortable, but this workflow works.

The last key feature is motion smoothing, we need this!
Without motion smoothing compute intensive applications are a bit laggy even with async reprojection enabled.

It seems like refresh rate is related to this. I find its much worse on 80hz, better but still noticeable on 144hz, still enough to be nauseating. It also possibly seems better immediately when launching SteamVR Home for the first time but it gets worse after.

On the RX 6800 XT, I have the same behavior. However, when using 80Hz, it is less visible than when using 144Hz. At 80Hz, it behaves like it has some delay; at 144Hz, there is visible stuttering.
Same on both X11 and Wayland session. KDE 6