I’m not sure of your setup, but there’s no way for this plugin to trigger its redirects when it’s not active. It sounds like there may be something else causing the redirects. You could have opened a support thread.
@putocoito The plugin adds the redirect URLs as post meta. There are no custom database tables, or server-level modifications (e.g. .htaccess). Without the plugin running, that post meta is essentially useless. The plugin serves as the filter for the redirects, so without it, the custom redirects aren’t added.
@renventura thank you for your explanation. Like a crazy I was searching in .htaccess and database. I tested your plugin in a new install and it looks it is working fine. (changed my rating to 5 star)
The cause should be something else in my clients website.