It literally is experimental. We have never deployed an mRNA vaccine on this scale before. This is the first time it has been done. The standard years of testing vaccines traditionally go through has not happened with this one. So it is, undeniably, objectively, experimental.
It is literally gene therapy. While most vaccines present a neutered form of a virus for your immune system to safely respond to and develop antibodies that will be useful in counteracting the version of the virus in the wild, mRNA vaccines quite literally insert themselves into your cells and try to insert that "training" RNA code into your immune system artificially without your body doing it on its own terms. This is what gene therapy is.
The medical boards based their decisions on the empirical research that doesn't exist yet? That's wild, they're time travelers?