Hello Blackhat2020,
yes VPNv4 routes are under the iBGP rules too so or you build an iBGP full mesh or you make the router in the middle route reflector server
note: this can be done at address-family level with
on R2:
router bgp xx
neigh R1:loop0 remote-as xx
neigh R1:loop0 update-source loop0
neigh R3:loop0 remote-as xx
neigh R3:loop0 update-source loop0
address-family vpnv4
neigh R1:loop0 activate
neigh R1:loop0 send-community extended
neigh R1:loop0 route-reflector-client
neigh R3:loop0 activate
neigh R3:loop0 send-community extended
neigh R3:loop0 route-reflector-client
use for iBGP loopbacks addresses advertised in your routing protocol and that are also used as LDP router-ids
Hope to help
Giuseppe