The multiserver variable seems that does not do what is stated on global.ini.php.
Set to 1 if you’re using more than one server for your Matomo installation. For example if you are using Matomo in a load balanced environment, if you have configured failover or if you’re just using multiple servers in general.
By enabling this flag we will for example not allow the installation of a plugin via the UI as a plugin would be only installed on one server or a config one change would be only made on one server instead of all servers.
This var does prevent that update link happears when mouse over on top warning is showning but if you click on it you are redirected to the normal update page as usual when multi_server_environment = 0 and can indeed update the core code.
The warning and layer appear in this location (sorry, I’ve already update and forgot to make the prints to put on this post):
As multi_server_environment = 1 should the plugins prevented to be updated too? The reason beside this is the same as the core code: if on multi server environment if you update a plugin on one frontend the others will be outdated and plugin / global functionality can be compromised.
Thank you, Pedro