tl;dr The immense government-driven spending boom on building infrastructure and real estate since 2008 has made the construction, real estate, and banking sectors disproportionately large compared to the rest of the economy, larger proportionally even compared to the Japanese economy before its real estate bubble crashed. The government is going to have to enact a potentially long period of enforced austerity on these sectors in order to allow other sectors, especially capital-intensive industry like electronics manufacturing, to catch up. But the current geopolitical climate and continuing pandemic conditions might put a damper on their desire to use these new industries in an export drive. Therefore China is likely looking at a significant period of low growth like it did in the late 90s.
Hence the Belt and Road. they can use it's construction as a valve for those industries, while domestically beginning a transition.