What I'm thinking about the peace deal offered by Russia is that Russia thinks it can get what it's offering, or slightly less, with force, and that Ukraine thinks it can get a better deal. That, or Russia is seriously bluffing, but I don't think they are because I don't think they're really expecting Ukraine to accept the deal. In other words, both sides seem pretty confident in their ability, at least compared to the options. No signs of the war ending soon. Instead, it seems like Russia thinks it can at least save face (on the home front - almost everything is already lost abroad), so it wants to continue the invasion.
One worrying view from some experts is that Russia could escalate the conflict outside Ukraine to save face. It's a really twisted thought, but it could allow Putin to twist the situation in his favour on the home front.