xEM is not very “brickable” infact it is very difficult to do it. What you are probably seeing is talk of the xm1 and flexm1.
From what I have found in almost I repeat almost all cases where a xEM has been “bricked” (not actually bricked) either a password was set using a blue clone or other chinese cloner or the programmer was removed while programming.
Have a search for xEM bricked Like this
Was fixed using a proxmark which is an amazing investment btw.