need to find the one flatpak installed on system

Mint cinnamon but I don't think this is distro or DE related though fix might be. Since the install last year I have seen a flatpak update process go by regularly in my sysmonitor. Usually doesn't take very long so I have let it go. But how can I find out what the package is that is installed? Must have been preinstalled - maybe I did and forgot. But I left kubuntu because of snap performance and didn't install any on here knowingly. Synaptic says one package installed in the whole count but doesn't tell me what it is. I did just search flatpak and also looked in the flatpak/exports/share apps folder also.

Is there a flatpak command that lists the currently installed pkgs?