What does China have to gain from having a neutral stance concerning the ownership of the Kuril islands?

Question

People's Republic of China once supported the Soviet Union's claim over the islands in the 1950s, however, after the Sino-Soviet split in the 1960s, China then turned to support Japanese sovereignty of the islands. After the Sino-Soviet border conflict in 1969, maps published in China began to mark the islands as Japanese territory with a note "Occupied by Russia".[92] During a news conference on July 27, 2021, Chinese Foreign Ministry spokesperson Zhao Lijian commented on the issue of Russian–Japanese dispute of the islands. He said, "It is China's consistent belief that the outcomes of the victorious anti-fascist war should be earnestly respected and upheld." Russia often cites "the results of the victorious war against fascism" to justify its ownership of the islands following the defeat of Imperial Japan in World War II. By saying "the results be respected", China apparently accepted the Russian argument.[93] During a March 20-21 2023 meeting in Moscow, Xi Jinping told Putin that China "does not take either side" regarding the territorial dispute.[94] This is a shift to neutrality compared to Mao Zedong who in 1964 said the islands belonged to Japan.[94]

https://en.wikipedia.org/wiki/Kuril_Islands_dispute

What does China have to gain from having a neutral stance concerning the ownership of the Kuril islands? After seemingly supporting Russia's claim, Xi said recently that China's stance was neutral concerning the ownership of the Kuril islands. This is surprising since China is an ally of Russia and Japan is allied with the United States and is aligned with the West on most issues. Does China have anything to gain from such a stance? It seems like it's just going to hurt their bilateral relationship with Russia.

Answer 1

There's no way to know this with any certainty, unless China makes some statement about their [true] motivations for this move, which seems unlikely to me they'd reveal publicly.

They could want some concessions from Russia in order to flip their public position back again. Those could be anything... But to stick to a somewhat similar matter, they could e.g. want Russia to publicly support them in the 9-dash line claims, which Russia has been pretty reserved on...

Russian-owned corporations are cooperating with Vietnamese companies on resource extraction within China's self-proclaimed Nine-Dash Line in the South China Sea, suggesting that Russia may be willing to pursue its own economic interests even when they contradict China's preferences. But Russia's willingness to challenge China goes only so far. Russia has not expressed clear support for China's Nine-Dash Line claim, but it has consciously avoided taking Vietnam's side and declined to mediate the dispute when Vietnam asked.

or anything else for that matter that China thinks Russia might concede on (e.g. those Russian corporations dropping that coop with Vietnam in South China Sea). Or simply be some kind of payback for not getting something [else] they asked for in private.