Though if I recall they did that only as leverage to get their own land back. That it was easier to take Russian territory than to retake their own. I seem to remember them saying they would happily withdraw in exchange for a return of their territory. Just a lesson that Russia doesn’t get to unilatterally decide where the front can’t be for their convenience. It’d be a strategic disaster to “play nice” and only fight on the fronts of the enemies choosing.