It’s likely not the chicken but the brine they soak the chicken in before putting them on the spit. Some people make a big stink over the type of salt used in the brining process. How do think the flavor gets into the chicken if not from the brine? Personally, I think they do a pretty good job with the brine, although I use plain old kosher salt on mine in a brine tub and then season it right before putting it on the spit.
I wonder if they have COVID vaccine in them?