The latest update of Steam has broken Team Fortress 2 in that everything appears in Black & White.
With thanks to the Wine Community for finding it, we have a temporary workaround while we work on a more permanent fix.
From the Steam launcher, right click on "Team Fortress 2" and select "Properties"
Click "Set Launch Options"
Add "-nod3d9ex" to the launch options
Click "ok" to complete the change
Launch Team Fortress 2