I am convinced that dress comes from Beatrix, looks too familiar.
Netherlands designer Ronald van der Kempt has confirmed on his Insta that the gown was his creation:https://www.instagram.com...ig_web_button_share_sheet
Modekoninginmaxima blog thinks it's a mix of various of his designs ... and the fabric is obviously one out of a current collection (right).
The fabric reminds me much at Van Gogh's "Flowering Garden with Path"
but I find it too busy for a formal gown.
The dress version on the far right looks all in all better than the bespoke she got (hate the ruffles/tiers), but would imho fit better for an outdoor summer occasion, but not for an indoor State Banquet end of October.