"Yavimaya is aware, but not always awake. You will know the difference when you see it."
—Karn

Sylvan Awakening

Until your next turn, all lands you control become 2/2 Elemental creatures with reach, indestructible, and haste. They're still lands.

Dominaria Promos

Dominaria

Sylvan Awakening affects only lands you control at the time it resolves. Lands you begin to control before your next turn won’t become creatures.

Sylvan Awakening doesn’t untap any of the lands that become creatures.

The lands affected by Sylvan Awakening stop being creatures as your next untap step begins, before you untap your permanents. If this causes any state-based actions to become applicable, or if any abilities trigger, those are handled during your upkeep.