This happened like two days ago, when one of the client sites went down. Upon inspecting the error logs, I found this:

SQLSTATE[HY000]: General error: 1835 Malformed communication packet

If you got the same error as the one above, don't worry, it's not your fault. According to this forum, a recent MariaDB update introduced a new bug for PHP versions < 7.3 that uses PDO and MySQL connectors. You can easily resolve this by simply upgrading it to PHP 7.3.

Hope this tip helps you out!