I don't see the point of setting
https://github.com/wikimedia/mediawiki-core/blob/c31fbf073e112526236d3afe6ef4dab3d5cd8e6f/includes/DefaultSettings.php#L4459
$wgGroupPermissions['*']['viewmywatchlist'] = true;
if we also have this:
https://github.com/wikimedia/mediawiki-core/blob/1ea16c08d70152062ba7feef62de8a69b3d08820/includes/specials/SpecialWatchlist.php#L41-L42
// Anons don't get a watchlist $this->requireLogin( 'watchlistanontext' );
Shouldn't
$wgGroupPermissions['*']['viewmywatchlist'] = true;
be replaced by
$wgGroupPermissions['user']['viewmywatchlist'] = true;
?