Opening file's "details" loads entire file

When opening a file’s “details”, it tries to load the entire file to show on the preview pane.

Is there a way to stop it from happening?

Nextcloud version: 14.0.4
Operating System: Ubuntu 16.04LTS
Apache version: 2.4.18

The output of your config.php:

<?php $CONFIG = array ( 'instanceid' => '', 'passwordsalt' => '', 'secret' => '', 'trusted_domains' => array ( 0 => '', ), 'datadirectory' => '/var/www/html/nextcloud/data', 'dbtype' => 'mysql', 'version' => '14.0.4.2', 'overwrite.cli.url' => '', 'dbname' => '', 'dbhost' => '', 'dbport' => '', 'dbtableprefix' => '', 'dbuser' => '', 'dbpassword' => '', 'installed' => true, 'filelocking.enabled' => true, 'memcache.local' => '\OC\Memcache\APCu', 'memcache.locking' => '\OC\Memcache\Redis', 'redis' => array( 'host' => '/var/run/redis/redis.sock', 'port' => 0, 'timeout' => 0.0, ), 'htaccess.RewriteBase' => '/', );