I think the following property is the problem:
linked items are represented as an array. to get all items from it, they must first be put into the correct form and then written to the item in a single update.
I often solve this like this:
Put the array of linked item into an iterator
with the text aggreagtor all ids can be packed into a string and this string is then inserted into the grapgh ql
So the final modul should have something like this as graph ql
Note This can also be done more efficiently, but this way it is very easy to understand