> Date: Sun, 19 Jan 2020 18:47:25 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 39188@debbugs.gnu.org
>
> > Like the one after Summary here? The cursor being at Manual, 1st line.
> > What is annoying is that it gets worse with my usual setting. It seems like
> > a race condition with something else.
>
> It's "your usual case" that I cannot reproduce.

Does your usual setup include scroll-conservatively?  Because with
that, I think I see what you describe.  And that problem started long
ago, in Emacs 23.4.