>>511191288 (OP)They never really had it, it was mostly undefended territory they passed through on the initial attack, and then retreated from when negotiations began in Istanbul.
Other than that, the Kherson area was given up when they retreated across the river to dig in before the Ukraine summer offensive, and the areas around Karkhov they were actually driven out of because they left a light picket force and stupidly assumed that NATO ISR wouldn't notice.