On Fri, 06 Aug 2021 13:00:30 +0200
Lars Ingebrigtsen <larsi@gnus.org> wrote:

> Tomasz Konojacki <me@xenu.pl> writes:
> 
> >> For example, "$package" is fontified like a keyword.
> 
> In what context, and in which Emacs version?
> 
> $package = foo;
> 
> is fontified like a variable in Emacs 28.

See the attached screenshot. Are you sure you aren't using cperl-mode?

> >  (defconst perl-font-lock-keywords-2
> > -  (append
> > +  (cl-concatenate
> > +   'list
> 
> Any particular reason to change from append to cl-concatenate here?

Because I'm concatenating three lists.