The West cannot afford to keep pumping supplies into Ukraine AND turn all focus onto China. A proxy war with Russia is one thing. Russia can hold its own but China’s military is booming and accelerating. With tech that, in many cases, is starting to, or already does, surpass the wests.

Since there is no way for Ukraine to hold on without western supplies then they will loose regardless when the west pulls out. However the “harder” they loose the less there is for the western oligarchy to plunder. So they are trying to shut things down as quickly and painlessly (for them) as possible.