why when i want to check an array query in my flutter project it doesn't get back any data?

Query.equal('categoryIds', ['6575abc183a6e1a9189a'])
i have a list of categoryIds inside my items When i want to apply the quires by the ids i send it it doesn't retrieve any data back. why does that happen?
but when i apply it on name it will bring that data back.

You're already aware from this post that it's currently not supported. The same query works on name precisely because it's not an array (i.e not containing multiple values). You can checkout the linked github issue to find some sort of workaround using full-text search but depending on your use case you may have to go with a different approach. https://discord.com/channels/564160730845151244/1181226010247708813

You can also look into appwrite relationships.

i just looked at the post i didn't realized there was post about it until i searched around. Query Doesn't apply to relationships which is why i separated the categoryIds to a separate Attribute.

Yes technically queries are not yet supported for relationships just yet but I'm still able to filter by queries in my flutter project (side project). Admittedly I haven't started using complex queries yet mostly because there are a few headaches/limitations working with relationships so I'm hesitating going all-in on them. I'm able to perform a query like this on a collection with a one-way many-to-one relationship with my users collection and it works. I would recommend you try it with dummy collections and see if it works for you. FYI, there are posts here where some* level of successful queries have been reported.

 queries: [
          Query.equal("user", ["userId"]),
          Query.isNotNull("user"),
          Query.orderDesc("\$createdAt")
        ]);