There is nothing from Lavrov that confirms that is the case. What he actually says:

On 7 April, Russian Foreign Minister Sergey Lavrov said that the peace deal Ukraine drafted and presented to the Russian government contained "unacceptable" elements. Lavrov said that the proposal diverged from the terms negotiators had agreed on.

So Lavrov makes an accusation: Ukraine changed the terms.

There is two possibilities here. Number one, Ukraine actually did change their acceptable terms (which is entirely possible and they have every right to do so). Or number two, Russia rejected that deal. Within that possibility, it could be because Russia was never considering the deal despite negotiations or it could be a change of posture.

We don't know what happened without further evidence. All we know is that the two sides seemed close to a deal, then someone changed their position.