10.11.8 hang on shutdown: "2024-05-27 9:00:12 0 [Warning] Signal handler thread did not exit in a timely manner. Continuing to wait for it to stop.."

After upgrading to 10.11.8, any attempt to gracefully stop the server (service mysql-server stop, service mysql-server restart, etc) results in this in the error log:

2024-05-27 9:00:12 0 [Warning] Signal handler thread did not exit in a timely manner. Continuing to wait for it to stop..

and then it just hangs forever. To be sure, I let one server sit there for several hours.

After downgrading to 10.11.7, the problem goes away.

I can reproduce this on all (10+) of my instances. All of them are FreeBSD 14.0-RELEASE-p6. Some are VMs, some are bare metal, some are Galera, some are standalone. I have not tested on Linux yet.