Pardon my English.
I didn't know where to post the report so if this is not the right place please point me in the right direction.
The problem would impact devices with limited space for '/var/log' (maybe the SteamDeck, I don't own one)

Kubuntu 23.04 (up to date)
X11

what happened:

1. launched the game:

DOOM (2016)
App   ID: 379720
Build ID: 2642713
Proton 8.0

1. after multiple hour long session
   found gigabytes of duplicate log entries in
   /var/log/syslog
   [slimed down log sample generated mid game attached]
   syslog.txt

multiple repeatitions per second

indeed no 'ChainsawKill' in

/mnt/gaming_volume_4/STEAM_GAMES/steamapps/common/DOOM/base/chroma_effect_files/
\mnt\gaming_volume_4\STEAM_GAMES\steamapps\common\DOOM\base\chroma_effect_files\

chroma is mentioned here
#896
I got it disabled in game settings

1. Verify integrity of game files:
   all 8123 files successfully validated

2. Download tab - Completed (4):

Steam Linux Runtime - Sniper
Proton 8.0
Steamworks Common Redistributables
DOOM

1. game launched again, navigated to game save slot selection screen and quit:
   [two slots with completed campaign]
   the same spam appeared

2. forced proton experimental, navigated to game save slot selection screen and quit:
   [two slots with completed campaign]
   the same spam appeared

repro:

1. Launch DOOM (2016) on linux
2. observe /var/log/syslog geting filled with spam about missing 'steamapps\common\DOOM\base\chroma_effect_files\ChainsawKill' even with verified game files