
why is this line not highlighted?
Defaults authfail_message="message"
If it is okay not to be highlighted, I wonder what standard it is decided on.

why is this line not highlighted?
Defaults authfail_message="message"
If it is okay not to be highlighted, I wonder what standard it is decided on.
Congratulations, you have found a bug in an open source program.
The parameter
authfail_messageis indeed missing from Vim's default syntax script forsudoers.Now, you have four options:
:help syntax),If you go with 2, 3, or 4, consider checking if other parameters are missing.