Proton Log: steam-15000.log
Game Log (from the Game itself, after Crash): lockdown.crash.txt
Proton Log: steam-15000_4.2.9.log
Game Log (from the Game itself, after Crash): lockdown.crash_4.2.9.txt
PROTON_USE_WINED3D=1: Crash
PROTON_FORCE_LARGE_ADDRESS_AWARE=0: Crash
PROTON_USE_SECCOMP=1: Crash
PROTON_NO_ESYNC=1: Crash
PROTON_NO_FSYNC=1: Crash
There's a fix for this bug in wine 5.22, once Proton is re-based in this version it should be at least playable
Looks like https://source.winehq.org/git/wine.git/commit/b1eedc7b6f7f5f22315e3c9dc23ebd2e65e77c58 is the commit involved.
Even if that commit makes it into Proton, Lockdown still suffers from https://bugs.winehq.org/show_bug.cgi?id=35727 (confirmed this myself) and maybe https://bugs.winehq.org/show_bug.cgi?id=32619 (hasn't been retested in a while).
Did a little test with Proton GE (using the 5.22 files) and there's a minor glitch with graphics

Wine bug 32619 (Savegame): I can't reproduce this issue with the Steam Version of the Game. My Savegames are here "steamapps/common/Rainbow Six Lockdown/data/save/game".
pcgamewiki notes that too. Maybe the Retail Version differs here.
Looks like https://source.winehq.org/git/wine.git/commit/b1eedc7b6f7f5f22315e3c9dc23ebd2e65e77c58 is the commit involved.
I compiled a local proton-5.13-4 Build with this pull request the game starts but after circa 5 minutes it crashed again. With both dxvk and wined3d.
Maybe this has something to do with applying the commit to an older wine version?
steam-15000_proton-5.13-4-springwurm.log
steam-15000_proton-5.13-4-springwurm_forcelgadd_off.log
steam-15000_proton-5.13-4-springwurm_forcelgadd_off_games_stack_trace.txt
steam-15000_proton-5.13-4-springwurm_games_stack_trace.txt
Tested again with both 5.13.5 and Proton 6.0-GE-1 and the same glitched line appear in my screen.
The only version which doesn't appear is with Proton-5.21-GE-1

And those shadow glitches appear in all of tested versions

Tested with Proton 6.3-1
The glitched line in the middle of the screen is now gone in the official Proton too

The only issue it remains now it's the lightning texture

For me, with proton-6.3-2, the two graphic issues are still present.
Logs:
i think these shadows are coming from the NPC's
Windows 7 with dxvk 1.8.1

Windows 7 without dxvk 1.8.1

I was curious and tested the game under windows 7 + dxvk 1.8.1 + AMD Radeon RX 570, with the same result.
Guess i try to create some trace files.
proton 6.3-2x1 2021-04proton 6.3-1x1 2021-04proton 5.21-ge-1x1 2021-01proton 6.0x1 2021-01proton 5.13-4x1 2020-12proton 4.2x1 2020-06PROTON_FORCE_LARGE_ADDRESS_AWARE=0:x1 2020-06PROTON_NO_ESYNC=1:x1 2020-06PROTON_NO_FSYNC=1:x1 2020-06PROTON_USE_SECCOMP=1:x1 2020-06PROTON_USE_WINED3D=1:x1 2020-06
Compatibility Report
System Information
I confirm:
Proton log
Symptoms
After the first intro, game crashes with the message "Read from location 00000000 caused an access violation."
Reproduction
Just hit play button