It's not recommended to use approvalStatus.
See this post from SAP
You can find below a copy-paste
Which Items Will be Synchronized?
Synchronizing can be done either on the entire catalog version
(easiest option) or can be done on a select group of items.
There are two typical use cases for filtering the items to be
synchronized:
There is a requirement to synchronize only approved products. The recommended practice is to avoid using the out of the box
"approvalStatus" attribute as you may want to synchronize products
which are not approved. The recommended practice is to introduce a new
attribute "readyForSync" as a boolean type. A business user or a
business logic would be responsible for setting the attribute to TRUE.
A restriction would guarantee that only confirmed products are
synchronized.
Synchronize a subset of items (such as products of a specific category) to a specified target catalog version.
One important consideration, in an enterprise setting where there are
many concurrent product managers, is the coordination of the
synchronization. The "readyForSync" flag can be helpful to schedule
products for the next synchronization run. However, it offers limited
granularity of control in an environment where there are multiple
teams managing their own lines of products. To provide a more granular
coordination, it is recommended to use a hybrid approach where the
"readyForSync" flag and the category-specific synchronization are used
together. This way, different teams managing different brands or
categories would not affect each other in unintended ways and it
offers more flexibility in terms of when the synchronization can be
run.
If you synchronize using a scheduled cron job then a search
restriction can be used with a dedicated synchronization user:
INSERT_UPDATE SearchRestriction|code[unique=true]|name[lang=en]|query|principal(UID)|restrictedType(code)|active|generate|Backend_Sync_Product|Sync|{item.readyForSync}=1|syncgroup|Product|true|true
As a side note, I don't know on which version you are working on.
It used to not work well in older version. (mentionned on this old page that will probably get deleted)
If you synchronize manually, then things can get tricky again:
Concurrent invocations from more than one business users result in some of the attempts aborting without an informative error message.
References to items in the same catalog version will not be synchronized unless marked as "copy by value" or "part-of".
Restrictions used for scheduled cron job synchronization do not work. Everything gets synchronized.
