Our database cluster is back to operation. Looks like broken innodb settings plus a corrupt filesystem on the data partition is not really what you want to see on the master node of a cluster. Luckily we could use one of the remaining nodes to restore a backup and make this one the new master. As we were on it, we decided to take the time and upgrade the whole cluster to the latest MariaDB 10.6 version, which is available in the server:database repository in OBS (as usual).