Re: whitespace-mode deactivated at end of line

[Eli Zaretskii]

> From: Emanuel Berg <incal@dataswamp.org>
> Date: Sat, 11 Jun 2022 07:24:13 +0200
> 
> Eli Zaretskii wrote:
> 
> > The red background that highlights trailing whitespace
> 
> Also why isn't that removed automatically on save?

Because it isn't any business of Emacs to second-guess the user's
intentions.  The user could, for example, be saving a partially
written file, or have any other valid reason for keeping the trailing
whitespace.

If you do want this automatic cleanup to be performed unconditionally,
customize the option whitespace-cleanup to do that.