Default route setup in LTM virtual server using Forwarding layer 2

Hello I need to understand this setup currently on one of the F5 LTMs. We have a default route setup under a virtual server list and the settings include Fast L4 as well 3 VLans (101,102,103) enabled under this setup. Then we have individual virtual server Forwarding Layer 2 routes setup for above 3 Vlans. I need to understand the reason or purpose behind this. we have another Vlan (201) which is part of routed mode and setup according to standard practice. In addition The Network default route is pointing to a Firewall. So all layer 3 traffic is taking one direction. My question is how Vlan 101, 102, 103 routing is working in current design? or is the F5 just bridging the vlans. there are VIPs setup which includes vlan 101,102 & 103 nodes in them w/o SNAT. I dont have any visibility on routers/switches or firewalls but if any further information is required i can get it.

Regards....