I'm not using LuCI for configuring the bird, just manually configured the bird4.conf for the VoIP and IPTV setup for Movistar.
I guess then I can use either bird1-ipv4, which uses less space, as it is only IPv4, if I got it correctly, and see if the conf file is the same or I should adapt it ...
That should work, if you used bird v 1.x in 18.06 the conf should work for 19.07. Or adapt to v 2.x and be future proof and escaping the IPv4 and IPv6 segregation from v 1.x, probably with a bit of learning curve for bird v 2.x configuration.