I can’t explain why your data is not correct. It’s almost as if the filter is being run via AJAX and has no idea of the page you are viewing. This is not possible as the post_object field (in v4) does not use AJAX.
You can see that on line 168 of the ‘core/fields/post_object.php’ file, the 3 filters are applied.
Would you mind doing some $_GET debugging in there?
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