Per its title, Psalm 63 was written when David was in which wilderness?

Answer: The Wilderness of Judah

Psalm 63's title places David in the Wilderness of Judah: "My soul thirsts for You... in a dry and weary land without water."

“A Psalm of David, when he was in the Wilderness of Judah. O God, You are my God. Earnestly I seek You; my soul thirsts for You. My body yearns for You in a dry and weary land without water.”— Psalm 63:1 (BSB)