I think it’s actually irrelevant really because I don’t reasonably see a situation where Putin is going to be prepared to negotiate. He seems to see this war as his lasting legacy (there have been rumors that he might have some terminal condition, possibly cancer), he doesn’t want his legacy to be defeat, he wants it to be victory even if it requires the death of about 80% of the population.
The only way that Russia would negotiate is if Putin is no longer in charge.