Random "Error Establishing a Database Connection" occuring once every 1 - 2 weeks

Question

I am running WordPress 5.9.3 on Ubuntu 20.04 using Apache and once every 1 - 2 weeks my website goes into a state of "Error Establishing a Database Connection".

Rebooting the server immediately fixes the error but I have not been able to identify the cause.

I don't know the exact time the last error occurred but here are the MYSQL logs covering the period.

2022-05-06T16:22:00.996887Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.26-0ubuntu0.20.04.2) starting as process 504960
2022-05-06T16:22:01.079528Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2022-05-06T16:22:03.133723Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.26-0ubuntu0.20.04.2) starting as process 504985
2022-05-06T16:22:03.213992Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2022-05-06T16:22:04.868275Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.26-0ubuntu0.20.04.2) starting as process 505007
2022-05-06T16:22:04.958503Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2022-05-06T16:22:06.780278Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.26-0ubuntu0.20.04.2) starting as process 505029
2022-05-06T16:22:06.865499Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2022-05-06T16:22:08.510855Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.26-0ubuntu0.20.04.2) starting as process 505051
2022-05-06T16:22:08.611824Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2022-05-06T20:02:49.462864Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.26-0ubuntu0.20.04.2) starting as process 756
2022-05-06T20:02:49.509926Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2022-05-06T20:02:50.551651Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2022-05-06T20:02:50.989221Z 0 [System] [MY-010229] [Server] Starting XA crash recovery...
2022-05-06T20:02:51.026852Z 0 [System] [MY-010232] [Server] XA crash recovery finished.
2022-05-06T20:02:51.135285Z 0 [Warning] [MY-013746] [Server] A deprecated TLS version TLSv1 is enabled for channel mysql_main
2022-05-06T20:02:51.135600Z 0 [Warning] [MY-013746] [Server] A deprecated TLS version TLSv1.1 is enabled for channel mysql_main
2022-05-06T20:02:51.138193Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2022-05-06T20:02:51.138570Z 0 [System] [MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
2022-05-06T20:02:51.195997Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '127.0.0.1' port: 33060, socket: /var/run/mysqld/mysqlx.sock
2022-05-06T20:02:51.196335Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.26-0ubuntu0.20.04.2'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  (Ubuntu).

There has been no obvious spikes in traffic and I'm really not sure what else may be causing this?