I think they're just desperate. Ukraine poured all their manpower into Bakhmut and into the Russian defensive lines this summer and burned up an incredible amount. They've lost this war and all the propaganda won't change the writing on the wall at this point. Especially now that Russia is leading a offensive of their own in all directions and steamrolling them.

There's really no other option other than NATO troops to change the equation at this point, I don't know if they're stupid enough to try though.