When you install a modpack from Modrinth, it is paired and locked to only contain the content from that modpack. By unlinking an instance, you can add your own content and also remove the link between your local installation and the modpack as available on Modrinth. Therefore, when you unlink a modpack, you can no longer automatically update or move between different versions.
To unlink an instance, go into the instance options, then go to the "Installation" section. Once there, press the "Unlink instance" button.
