For devices that broadcast in both ANT+ and ANT+ FE-C, Zwift should only allow pairing with ANT+ FE-C.
ANT+ FE-C is a newer standardized protocol and it works much better than plain old ANT+. In fact, connecting your trainer to ANT+ rather than ANT+ FE-C is a leading cause of dropouts in Zwift.
So if a trainer offers both, Zwift should only offer the ANT+ FE-C protocol in the pairing screen. Having both is very confusing since most people don’t know the difference and one is far superior to the other.
Lastly, although my Wahoo Kickr 2018 offers both, Zwift sometimes automatically connects to the ANT+ instead of the ANT+ FE-C even though FE-C is the only protocol I ever use.