IIRC, the other times this has come up it has been a problem that can be fixed by running a script. +shell.

nikolau.mk wrote:

The problem should be fixed by whom? I am not quite familiar with these kind of things.

best

(In reply to comment #2)

The problem should be fixed by whom? I am not quite familiar with these kind of
things.

If my understanding of the fix is correct, then a shell user should be able to fix this. When a shell user is looking for things to do, they'll look for the shell tag and find this bug.

'wgArticleCountMethod' => array(
'default' => 'link',
'enwikibooks' => 'comma',
'ptwikibooks' => 'comma',
),

https://www.mediawiki.org/wiki/Manual:$wgArticleCountMethod

This is not a bug, the count was wrong before and has been corrected now, 13 days before this bug was filed (see bug 33253 comment 10). Probably, pages which have been deleted at some point without the count being decreased.