I know that but the Western allies kept Hitler from concentrating his forces against Russia. Also, the West through Arctic convoys gave Russia supplies. Finally, it was the West which bombed Germany not Russia.
Russia would gain Crimea, the US military would no longer be in Europe, sanctions against Russia would be lifted, and with UK and French troops in Ukraine, Russia would not be able to conquer Ukraine.
By 1944, Russia had fully recovered from the German invasion and was a powerful military. That was not the case in 1942. When Hitler launched his 1942 summer offensive, he had to keep units in the west to repel any invasion of France by the Western allies.
Numbers alone don't count. During World War II, Germany could have conquered Russia if it didn't have to fight the powerful US in the west. That's the reason Putin might accept the plan. Without the US in Europe, Putin might think he can conquer Europe.
This is what the EU should propose to Putin. Russia will withdraw from all land it seized from Ukraine after the 2022 invasion. NATO would be dissolved and replaced with a European alliance. Ukraine and Canada would be permitted to join but not the US. If Putin doesn't accept the proposal, the UK and France would send troops to Ukraine.
I know that but the Western allies kept Hitler from concentrating his forces against Russia. Also, the West through Arctic convoys gave Russia supplies. Finally, it was the West which bombed Germany not Russia.