> Xi has moved the system/party
Because Xi has circumvented several of the most important limitations (term limits, seniority) on party and state leadership, there is no
system anymore. AFAIU, since Mao died, ultimate power was vested in the Politburo Standing Committee (PSC). Cycling out of leadership posts after two terms was simultaneously both the concrete recognition and reflection of where ultimate power was truly vested.
The bribery was an artifact of how power was shared in the PSC, and how the members jockeyed to maintain a balance of power. At a high level it wasn't corruption, per se, but the system through which the PSC members could exert influence when they weren't seated as the President, Chairman of the Central Military Commission, etc. It effectively operated like the checks & balances of Western institutions. If a PSC member opposed a policy preferred by the President, those backchannels to the party base and to industry was how they could push back, and ensured the posted leaders always had to acquiesce, to some degree, to the PSC members.
In as much as there was corruption, well that's the price you pay for not having a transparent system of governance with an independent civil service and independent judiciary without concentrating too much power into the hands of a (hopefully) benevolent dictator.
The problem is that all the senior leaders from the Maoist era are gone. The norms of the PSC were instituted intentionally to avoid the reemergence of Maoist extremism. This generation doesn't appreciate the critical importance of the power-sharing norms within the PSC. They think they can have their cake and eat it too: preserve the one party Communist system and provide streamlined, efficient governance, without instituting democratic, rule-of-law reforms. They apparently don't appreciate the fact that once the PSC is effectively dominated by a single individual, then the one party system is de facto extinguished--the party becomes subservient to a single individual.
More importantly, like many people they don't appreciate the fact that whether in democracy or single-party rule (which has a sort of internal democracy), some amount of organizational inefficiency is the price you must pay to keep power from centralizing. Maximum organizational efficiency can only be achieved in a dictatorship because that's the only way, theoretically, to maximally minimize transaction costs. But over the long-term history has shown that optimizing for short-term efficiency is a really bad idea and it tends to result in very inefficient long-term outcomes.