Eg. getAllSites, getSitesFromIds, getSiteFromId, ... pretty much all methods that return one or more sites and not only site ids.

What those methods do is the following:

PHP
$sites = array() // get sites in some way eg $this->getModel()->getAllSites()
Site::setSitesFromArray($sites);
return $sites;

It actually returns the raw site information as returned by the model / database but setSitesFromArray triggers a postEvent to let plugins change or extend the site information. As we do return only $sites and not the modified sites array the values might be incomplete.

This sometimes results in weird code like this:

Site::clearCache();
APISitesManager::getInstance()->getSitesWithAtLeastViewAccess();
$sites = Site::getSites()

Apart from this not making any sense it causes the site cache to be cleared which results in many more site queries although the site information was already fetched previously.

Ideally the site cache would not post an event as it is only a cache and should not contain any logic.