It was probably some power outage what caused the issue. I've tried forcing recovery by setting the `innodb_force_recovery` variable incrementally, and none of the recovery modes seemed to magically fix the problem. Using higher modes, at least MariaDB starts, but databases are corrupt and crash MariaDB as soon as I try to interact with them using the client. It's not like I had highly important data in my databases, but I think it's worth trying to fix, in case it happens again when I do have important data stored in it. I attached the systemd logs.