So unlike money-market funds, these private-credit funds can gate withdrawals and extend and pretend by turning cash coupons into PIKs. So I don't actually see credit concerns directly driving liquidity issues for the banks that didn't hold the risk on their balance sheet glares Germanically.
Instead, I think the contagion risk is psychological. Which is an unsatisfying answer. But if there are massive losses on e.g. DBIP and DB USA halts withdrawals, then the 2% stock loss Morgan Stanley suffered when it capped withdrawals [1] could become a bigger issue.
[1] https://www.wsj.com/livecoverage/stock-market-today-dow-sp-5...
Or never invoked. It's a safety feature for the fund and, arguably, systemic stability.
People eventually want to spend their money.