Steps to reproduce

1. clean install nextcloud
2. add conditional overwrite settings to config.php
   'overwritehost' => 'my.domain.com',
   'overwritecondaddr' => '^192.168.0.1$',

Expected behaviour

Hostname should be overwritten when request comes in via 192.168.0.1, otherwise NOT.

Actual behaviour

Hostname is always overwritten

Server configuration

Operating system:
official Docker Image on different Docker Hosts

Nextcloud version: (see Nextcloud admin page)
12.0.3.3

Updated from an older Nextcloud/ownCloud or fresh install:
fresh

Where did you install Nextcloud from:
docker

Nextcloud configuration:

<?php
$CONFIG = array (
  'htaccess.RewriteBase' => '/',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'apps_paths' => 
  array (
    0 => 
    array (
      'path' => '/var/www/html/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 => 
    array (
      'path' => '/var/www/html/custom_apps',
      'url' => '/custom_apps',
      'writable' => true,
    ),
  ),
  'instanceid' => 'xxx',
  'passwordsalt' => 'xxx',
  'secret' => 'xxx',
  'trusted_domains' => 
  array (
    0 => '192.168.99.100:9000',
  ),
  'datadirectory' => '/var/www/html/data',
  'overwrite.cli.url' => 'http://192.168.99.100:9000',
  'dbtype' => 'sqlite3',
  'version' => '12.0.3.3',
  'installed' => true,
  
   'overwritecondaddr' => '^192\.168\.99\.11$',
   'overwritehost' => 'my.domain.com',
  
);

Code causing Troubles...

Problem is in File .../lib/private/AppFramework/Http/Request.php in Method 'private function isOverwriteCondition($type = '')' ... type is empty when checking for e.g. Host-Override in Method 'getOverwriteHost' ... so with empty type check override method (isOverwriteCondition) always returns true cause of:

...
return $regex === '//' || preg_match($regex, $remoteAddr) === 1 || $type !== 'protocol';
...

-> type === '' ... so $type !== 'protocol' is always true ... so method always returns true in this case.