The bank runs are fallout from the financial contagion from the R/E developers like Evergrande.
And the fact for 2 decades the local banks have acted like an atm machine for corrupt local officials, they rubber stamped loans from crony business projects associated with the those officials, with bloated budgets that included huge payoffs to those officials for getting those loans approved.
At the time everyone wins, the projects inflated the region’s GDP which made the official look good, and China economy was growing so fast that the good loans the bank has on the books yielded enough profits to offset these questionable loans. Evergrande is just the tip of the iceberg.
But that is no longer true. China’s economy has slowed down drastically the last few years, some of it covid related, even private loan to good (formerly) private businesses are failing, and consumer real estate defaults have shot up too.
The only thing preventing these banks from collapsing is basically the government preventing individual depositors from withdrawing their money.