You would, and he did. You name, and explain, what tools you used when submitting an art piece. The general public get to see the "via MidJourney" tagline, and

You would, and he did. You name, and explain, what tools you used when submitting an art piece. The general public get to see the "via MidJourney" tagline, and the judges get to have a bit further read of the description of how it was made, during the submission. Nothing here was hidden. And, if we ignore that this gallery was for digital art, you submitted pencil, then you would say "in pencil", and you would describe the place, and who was present, when you were making your piece.