Everyone wants a solution for the war, and to the Ukrainians the solution isn't to surrender to Russia.
Russia IS on the back foot.
Plenty of evidence out there, this has already been debunked multiple times to the point that even the Russians don't use this talking point anymore, go look it up yourself.
Russia's goal wasn't just a part of Ukraine, it was the complete take over of Ukraine; they've just realized that Ukraine won't go down without a fight, and had to significantly downgrade.
If Ukraine surrenders it's captured territory, it knows that Russia will just rebuild its army and try again later (Russia has a history of this).
Russia also won't have a choice in the matter, it's already been severely depleted to the point that it is no longer considered a military threat to its main adversary, the USA. They will give up.
Also, keep in mind, Ukraine also controls a chunk of Russian territory as well.