

That is correct, there were border raids which prompted the invasion, but the Sino Soviet split is what caused the worsening relations which led to that. Basically, the invasion was cringe, even if there was some justification for it, but what was more cringe was the repudiation of Stalin and the revisionism in the USSR that followed by corn boy.
Purchasing power parity is imperfect but a step in the right direction, but direct metrics that aim to summarize all economic activity in a country generally don’t capture much nuance.
Trying to separate non productive things like finance capital jerking itself off and productive things like tangible goods and services is hard since the line between useful service and frivolous bullshit can be quite thin. It might be better to try and compile multiple metrics into an index that measures things like per capita income, purchasing power, home ownership, access to healthcare, education, transportation etc. but that’s a massive undertaking in it’s own right.