> >> Any hints for this phenomenon?
> >
> > A form-feed char (Control L) has from the outset been used
> > as an ASCII control character, to cause a new page to be
> > advance (fed) on old printers.
> 
> But they are also transformed into buttons, a pretty exotic
> interactive feature, in `gnus-article-mode' buffers :)
> innit?

You can also customize how you want ^L chars displayed,
to appear as better page separators.  See Pretty Control L:

https://emacswiki.org/emacs/PrettyControlL

https://www.emacswiki.org/emacs/download/pp-c-l.el