Why is Sesse depth in plies?

As google says, a ply is a half of a move (a turn by 1 player). And Sesse shows depth in plies. So does it mean we should divide it by 2, and Sesse actually has lower depth than lichess cloud analysis? Am I missing something?

All engines show depth in plies.

"Depth" in modern chess engines like Stockfish doesn't really correspond to plies. Stockfish uses depth to indicate how many times it has gone through its deepening iteration, but that number does not correspond to how many plies deep it has searched. Some lines will be searched much deeper; many, much shallower.