You can never say it has never happened, because there are over 100,000 congregations, and some wacky elders out there, but it was never policy to disfellowship someone for a beard, I’ve never heard of a case, and it seems unlikely. If ever there was such a case the elders involved might explain the situation with reference to other factors in the case such as attitude and other behaviours rather than saying they disfellowshipped because of a beard alone.
I wonder if anyone has ever been disfellowshipped for a tattoo. Not for a discreet one but for a visible one with a dubious depiction, or all over face or head, I can imagine it happening, though I don’t know any examples of that either.