Currently northd incremental processing for lflow fails when IGMP groups are added/removed.  The I-P node dependency is:

SB.IGMP_Group -> en_lflow

And this doesn't have a change handler.  If multicast snooping is enabled IGMP groups are created/updated in the OVN Southbound database every time an IP multicast receiver registers/deregisters for multicast traffic.

Such updates of the SB IGMP table trigger a full recomputation of the lflow node which can be costly at scale.