That 80% would be the contract price differences, but they have agreed to waive the export duty, bringing down to a 43% increase.
But remember, we are talking about increases from below market rates, even at the time of the previous contract. They were “gifted” a discount to begin with.
They were discounted in exchange for port leases (not needed after the take over of Crimea) and part of the bribe to get Ukraine to give up their nukes (which they unwisely did, trusting promises), and to pay for the Russian use of Ukraine’s pipeline to transport gas.