Russia Ukraine war, page-171418

And for Crimea, look into the North Crimean Canal. 85% of water was blocked by Kyiv, in order to damage the people living there. Resource warfare. I don't think Crimeans would be too happy to be returned to the folds of their caring Kyiv government.
In addition, it probably wouldn't help that Zelensky himself has mocked Crimea's water shortages for cringe comic effect.