Issue resolved. It is no fault of the container. Apparently my phpMyAdmin was hacked. It is similar to this incident on bitcoinabuse.com. I'm going to assume my entire server is compromised at this point. Good thing nothing critical was on the server.
What happened:
I run a single OLS+WP docker stack (litespeed+phpmyadmin+mariadb) in a Ubuntu OVS server.
One day, my Wordpress sites report "Error establishing database connection."
Navigating to website.com/wp-admin will show a page with the following message: "We were able to connect to...