GB et al,
Airbus adopted shunt antennas in the fin from the beginning. I don't know how well they understand the dynamics, but feeding hundreds of amps into a carbon fiber fin makes me wary.
On the 388 the HF shunt sits on the
metal leading edge strukture and has [a lot of] dedicated bonding paths/plates on the upper fus to feed back into the HF crate at the [very] aft upper deck.