If you browse your [LabVIEW 20xx] folder in LabVIEW 2021 SP1 or later, you'll notice things look different. More specifically, all LLBs are gone, and have been replaced with folders that share the same name as the original LLB (including the .llb extension). This change includes the following LLB -> Folder conversion:
[LabVIEW 20xx]\resource\plugins\PopupMenus\support\Shortcut Menu Plug-In Template.llb
Due to this change, whenever you use the 'Create Shortcut Menu Plug-In From Template.vi' tool to create a new plugin, it is created as a folder instead of an LLB. Thankfully, the plugin will still work when it is implemented as folder instead of an LLB. However, if you prefer your plugins to remain LLBs, you can use this approach to convert the template to an LLB, which means all future plugins you create will still be created as LLBs.