I think that says more about their vast investment in other forms of power (particularly renewables) than it suggests a lack of investment in nuclear.
One armed bandit says explore as well as exploit. This delta you cited indicates the pendulum currently is more exploit than explore, but its not a static equation.
TBH this part seems key, even PRC couldn't operate full western designs reliant on western industrial capacity economically, part of it was simple incompetence of western supply chains (business closures / regulatory drama / sanctions). Nuclear seems viable once you strip out a lot of the politics that makes them uneconomical, hence PRC had to indigenize the designs since once western supply chains enter picture, the schedule goes out the window.