So things you think are too simple.
The Ukrainian war is regarded by many Chinese anti Russian factions as another expansion of Russian chauvinism, and should actively participate in containment of Russia,
Historically, Russia has really hurt too many of its neighbors.
The entire northern fringe of China was captured by Russia. Mongolia's independence has deprived China of the entire northern strategic buffer zone, as well as the territory of millions of square kilometers in the Far East(even including the population expulsion and slaughter led by Tsar Nicholas II).
Up to now, all the major cities in the Far East must use the place names of China in the past on the map of China. You can see the true attitude of the Chinese government towards this area.
China's nongovernmental commercial activities in the Far East are not pleasant. The Russians always confiscate the farmland contracted by the Chinese in the Far East for various reasons.
In addition, as if on purpose, the Russians have built bridges over the Tumen River (China's only outlet to the sea in the Far East) that are impassable to large ships.
We have ample reasons to believe that Russia does not want the Chinese to have too much activity in the Far East. The idea you put forward must be based on sufficient trust between the two sides, but the Russians are obviously taking strict precautions against us in the Far East.
One additional sentence: Russians have no scruple about the feelings of the Chinese on this historical issue, and their behavior will only further aggravate anti Russian sentiment. Even Deng said, "In history, the Russians have taken the most territory from us".
The Russians should thank the Soviet era. Our friendship for the Russians is entirely based on the memory of communism.