I see a possible precedent here. Its a take over border issue. Khrushchev gave the parcel to Ukraine for saving Russia’s ass in WWII. Now they want it back? The German borders were moved back westward stopping at the Oder river. How long before they’ll want their eastern territory that is now Poland?
Khruschev didn’t gave parcel over WWII. Khruschev gave Crimea because the bridge between Crimea and mainland Russia was destroyed in 1944 and there was no connection. It was easier to administer from Ukraine because it is a peninsula and has indeed land connection to Ukraine. It wasn’t a problem since Ukraine and Russia were both states of a single federation.
If you are to go deeper in history Ukraine in current form NEVER existed as a nation-state before 1992.
It didn’t exist ever in any form before 1920 and then only briefly. Any source claiming otherwise is a Bolshevik propaganda designed to ruin Russian Empire by inspiring any kind of secessionist movement and later its adaptations by Nazi Germans mainly for the same purpose but targeting USSR.
Once again all of the above don’t exclude the possibility of Ukrainian independence as a fact recent reality.