Another Hint

In what sense are the following paintings all "metaphysical compositions"?

David Hockney's "Going up Garrowby Hill", 2000.

Giorgio de Chirico's "Metaphysical Composition (Composizione metafisica)", 1914.

Diego Velazquez's "Las Meninas", 1656.

Jay provided an important clue: "we're looking from the eyes of Velazquez as he paints his own reflection in a wall-sized mirror".

My first hint tried to suggest that Hockney's painting is probably not a picture of Garrowby Hill but a picture of, well, going up it, which is something Hockney often did in his youth.

The third hint comes to us from an unlikely source, namely, John Henderson's Pliny's Statue (University of Exeter Press, 2002). On page 221 he points out (more or less in passing) that Paul Eluard renamed "Composizione Metafisica" as "Portrait d'Artiste par Lui-même" and that it accordingly appeared under the title "Self Portrait" until the 1950s.