loops = list()
faces = bm.faces
while faces:
        faces[0].select_set(True) # select 1st face
        bpy.ops.mesh.select_linked() # select all linked faces makes a full loop
        loops.append([f.index for f in faces if f.select])
        bpy.ops.mesh.hide(unselected=False) # hide the detected loop
        faces = [f for f in bm.faces if not f.hide] # update faces