Eval returning null instead of empty array which is the real value in table

I have an eval which is returning null instead of an empty array. I am relying on the array structure so it is necessary that this field is returned as (empty) array and not null.

Why is this happening? If I query the object via the "direct" endpoint by id it returns the empty array like it should.
Unfortunately I also can not set a default value via filter in an eval.

The eval:

The databases entry:

The response:

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