Please follow these steps:
Make sure your GPU driver is up to date
Steam > Library > Right click on the ETS2 > Properties > Local files > verify the integrity of the game cache.
My Documents > Euro Truck Simulator 2 > Delete the '' Config. Cfg '' file and then open a new profile.
and if nothing works, you can change your tag's color manually:
Go to your Documents
Open your ETS2MP or ATSMP folder
Open the config.txt file
Search for something called " "tag_color" ", which has some numbers behind it.
Those numbers behind this "tag_color" is the Decimal code of a color. If you want to get your own color from somewhere, ask for the color code. This can be something like "#78909C", which is the color of the Community Moderators here on the forum.
If you have this color code, use the following website to change your Hexidecimal code to a Decimal code: https://www.mathsisfun.com/hexadecimal-decimal-colors.html
The example color I used, is the following in Decimal code: "7901340"
Use this code to replace whatever is placed behind "tag_color" in your config file.