https://glpi-user-documentation.readthedocs.io/fr/latest/modules/tools/knowledgebase.html

Only public FAQ items are visible to users of simplified interface. Other elements are visible only to technicians via standard interface. FAQ items are public to everyone (within their entity) that has access to read FAQs. The additional visibility restrictions will have no affect in this case.

Are you talking about the last case ? For public FAQ articles, the restrictions on entity/profiles/groups/user are not enforced.

No, this does not affect public access
In fact when you are not connected: ok for me to see the articles of all the entities from the simplified interface.

But if you are logged in, you will not see all the articles but only those that meet the criteria

Have you checked the link above ?
The documentation state clearly that any public FAQ ("Put this item in the FAQ") will be visible to all self-service users without restrictions.

Yes but you have 2 cases :
with or without this parameter :

I'm not saying that I agree with it, but that's how its defined.

I have no opinion about the way to filter things, but we recently had many PRs about this. We should probably add some tooltips next to some fields to clarify how it affects visibility. It could help both end-users and developers.

Yes but I do not agree with this note :(

The targets are here to define who can see the articles (entity, profile, group, user) & I think it should be the same on a simplified interface (except with anonymous access)

When you have several entities (like IT and HR), it is normal, I think that the user having access to the HR entity, only sees the articles of his entity.

Actually, after reading the doc again we may be indeed missing the entity check:

FAQ items are public to everyone (within their entity)

So public articles should in fact enforce entity checks if they are defined (but still ignore profiles/groups/users checks).

Maybe something like this ?

diff --git a/src/KnowbaseItem.php b/src/KnowbaseItem.php
index 404c1195c0..16db20fded 100644
--- a/src/KnowbaseItem.php
+++ b/src/KnowbaseItem.php
@@ -667,7 +667,8 @@ class KnowbaseItem extends CommonDBVisible implements ExtraVisibilityCriteria
     /**
      * Get visibility criteria for articles displayed in the FAQ (seen by
      * helpdesk and anonymous users)
-     * This mean any KB article tagged as 'is_faq' should be displayed
+     * This mean any KB article tagged as 'is_faq' and with valid entity 
+     * restrictions (if defined) should be displayed
      *
      * @return array WHERE clause
      */
@@ -675,10 +676,22 @@ class KnowbaseItem extends CommonDBVisible implements ExtraVisibilityCriteria
     {
         $where = ['is_faq' => 1];

-        // Specific case for anonymous users + multi entities
         if (!Session::getLoginUserID() && Session::isMultiEntitiesMode()) {
+            // Specific case for anonymous users + multi entities
             $where[Entity_KnowbaseItem::getTableField('entities_id')] = 0;
             $where[Entity_KnowbaseItem::getTableField('is_recursive')] = 1;
+        } elseif (Session::getLoginUserID()) {
+            $where['OR'] = [
+                // Items with valid entity restrictions
+                [self::getVisibilityCriteriaKB_Entity()],
+                // Items that have no entity restrictions
+                'NOT' => [
+                    KnowbaseItem::getTableField('id') => new QuerySubQuery([
+                        'SELECT' => 'knowbaseitems_id',
+                        'FROM' => Entity_KnowbaseItem::getTable()
+                    ]),
+                ]
+            ];
         }

         return $where;
(

Closed in favor of #13455.