Diplomacy needs a mutual intention to engage, as well as there being some kind of 'landing strip'. Neither, Imv, are present in this, so anything is just performative guff.
You might also look at the example of Macron, who tried diplomacy. It didn't just not work, but he was hung out to dry by Putin. Can't see many queueing up to made fools of in his place.
If Russia asks China to mediate and help choreograph then I think we can take that as a serious attempt to end this, but until then people are going to see anything, whether from the west or Russia, as just part of Putin's information operation.