Nowadays a Yammer Community gets a corresponding Microsoft 365 Group (Office 365 Group, Unified Group). In your work as an SPO Admin, you might need to differentiate “ordinary” Modern Team Sites from those ones that were created for a Yammer Community. They both have GROUP#0 as Template. On the actual SPO Site object, there is nothing that you can use to differentiate those. Neither you can use the Office 365 Group information.