The apitrace is empty. Rule of thumb: if it's much smaller than 100 MB, it's probably not very useful. I don't have the game, so can't test.
Anyway, tons of d3dcompiler messages in the log, so trying a native d3dcompiler_43 might help.
Also, plaase test if wined3d works better.
Game doesn't start with PROTON_USE_WINED3D=1
I did this: WINEPREFIX=/media/data/SteamLibrary/steamapps/compatdata/20510/pfx/ winetricks d3dcompiler_43
winecfg shows this:

Wine version used for winetricks
wine --version: wine-4.9 (Staging)
Same distorted screen issue.
Should game start with apitrace libs? Because when i tried to start game with them, game engine bug trap catched something and game didn't started.
Also with wined3d and proton log enabled i got 700+MiB log.
Full of this:
Index just increasing.
40691.820:0027:0028:fixme:d3d10:d3d10_shader_reflection_GetConstantBufferByIndex iface 0x1004508, index 25668 stub!
40691.820:0027:0028:fixme:d3d10:d3d10_shader_reflection_GetConstantBufferByIndex iface 0x1004508, index 25669 stub!
40691.820:0027:0028:fixme:d3d10:d3d10_shader_reflection_GetConstantBufferByIndex iface 0x1004508, index 25670 stub!
40691.820:0027:0028:fixme:d3d10:d3d10_shader_reflection_GetConstantBufferByIndex iface 0x1004508, index 25671 stub!
I think i found core of issue: anti-aliasing.
If i enable it, image is distorted.
I talked with some stalker fans, they said, that on their systems(windows) image is little bit distorted, not like mine.
Also i found source code of engine.
Source code:
patch 1.5.06.tar.gz
Some info about dir. structure if you are interested:
Engine source code: http://files.xray-engine.org/xray_engine/src/soc_cs/
Password in: stk-src-tags.txt
You need tags/clear sky/patch 1.5.06/ rendering code in Layers directory
This happens with latest DXVK, i regenerated my wine prefix for this run, so it's clean version made by steam:
https://github.com/doitsujin/dxvk/commit/1e0fe36cae8128820f8a2314060e139f5ec6de93

proton log:
https://gist.github.com/XakepSDK/47defbf4fa13277fdef99a18ccb645e1
My friend made apitrace on windows:
https://drive.google.com/open?id=1b1pZzUyzws7G0Pm9Zc-syplulhKL6nm8
Is apitrace useful? I can get another one if you want
Haven't looked at it yet.
Does this work if you disable MSAA? It looks like the game tries to sample an MSAA texture like a non-MSAA texture, which is not supported in Vulkan and cannot be emulated in a performant way.
Looks like it's working if i completely disable AA.
If it's not hard, could you make workaround so i can test it?
Unfortunately no, as mentioned there is no way to implement this behaviour properly without making the game run at like 1 FPS.
Guys from community said, that this stretching issue happens only in main menu.
Does this mean, that i will have 1fps only in main menu?
I'm not going to implement a workaround because it's too much work for little to no practical return.
Thanks for debugging things. Close if you wish.
Game starts flickering after some time playing. Hard to make screenshot.

Does the game support D3D9 or work properly on wined3d? I cannot fix that broken engine.
Yes, but most features are on DX10 renderer. Previous screenshot was made without AA.
Flickering during rain is vanilla issue that happens on all of the default DirectX renderers and has nothing to do with DXVK.
Game does not have any issues for me with proton 5
Everything works as excepted, except anti-aliasing in stalker soc and clear sky, but this is game bug
Software information
STALKER: Clear Sky (20510)
Black screen or distorted screen.
Everything maxed out, game restarted, then maxed out again, first max out opens more settings after restart.
Here's game settings, should be in
$GAME_DIR/_appdata_/, name:user.ltxuser.tar.gz
After i alt+tab some times, graphics start to draw, but distorted.

System information
Apitrace file(s)
STALKER Clear Sky_apitrace.tar.gz
I just dropped 3 dlls from https://github.com/doitsujin/dxvk/wiki/Common-issues
without disabling dxvk because it won't generate these files.
I'm not sure if this is correct, because this https://github.com/doitsujin/dxvk/blob/master/issue_template.md page says, that i should disable it.
Log files
STALKER Clear Sky_1_log_broken.tar.gz