Since Chinese banks started selling perpetual bonds internationally in 2014, global bondholders have accepted that if Industrial & Commercial Bank of China Ltd., the world's largest lender by assets, faces insolvency, the least of their concerns is whether they'll be bailed in. Beijing won't let its large institutions fail.
Large -- note the adjective. There's no guarantee that the government won't let a couple of smaller banks go belly-up. That point may have been lost on some international investors.