10.5.8 fails to startup on approx 10% of ubuntu focal deployments

We run many CI jobs a day for openstack-ansible and deploy MariaDB 10.5.8 across several OS per patch tested. Anecdotally this has started happening on Ubuntu Focal since we upgraded the deployed version to 10.5.8.

Roughly 10% of the jobs are currently failing because MariaDB fails to startup correctly. The service log is filled with

{{Jan 28 09:38:23 aio1 mariadbd[35395]: --Thread 140426648426240 has waited at ha_innodb.cc line 4704 for 391.00 seconds the semaphore:
Jan 28 09:38:23 aio1 mariadbd[35395]: Mutex at 0x55cc9e14de40, Mutex LOCK_SYS created /home/buildbot/buildbot/build/mariadb-10.5.8/storage/innobase/lock/lock0lock.cc:461, lock var 2
Jan 28 09:38:23 aio1 mariadbd[35395]: InnoDB: ###### Starts InnoDB Monitor for 30 secs to print diagnostic info:
Jan 28 09:38:23 aio1 mariadbd[35395]: InnoDB: Pending reads 0, writes 0
Jan 28 09:38:23 aio1 mariadbd[35395]: InnoDB: ###### Diagnostic info printed to the standard error stream}}

A complete dump of the service log is here http://paste.openstack.org/show/802413/

This has been reproduced outside a CI environment in a focal virtual machine by running the same deployment code, and on the occasions when it is stuck in this mutex lock state, restarting the service gets things working again.

Any pointers on how to debug this further would be really helpful.