It will only end with Ukraine's agreement, and it's safe to say they won't be as anxious to have it end on or by May 8th precisely because it's a Russian holiday. No one would blame them. They'll at least delay any truce to a substantial term beyond that. And if it's true Russia has changed plans and reducing the scope of the "military operation" to eastern and maybe southern Ukraine, then it means Ukraine will have some kind of empowerment to regroup.
Russia will not, at the very least, abandon the Donesk or Luganst states, and Ukraine is already accustomed to their part 8 years of civil war there. So I can see this dragging on well into 2023, and maybe several years more. Saying it'll be over in a month is kinda like instituting covid lockdowns and mask mandates for a month to "flatten the curve".
Russia has absolute air and missile superiority. Putin does not want to waste lives taking territory he has to return. He might want agriculture to get going again in the May planting season. China has a terrible crop forecast. He can sell everything they raise for gold and oil and real products people can use. All America can do is print money.