I don’t own the Flight Sim Labs A321 for MSFS but ever since it was released it shows up in the Hub as installed outside MSFS. It’s marked as available to update. I tried updating and removing it, but it soon reappears as ready to update.
I do have the FSL Airbus installed in P3D, but that is handled by the FMS Data Manager and is up to date. The Hub should only show things you have installed.
Kevin