Actually there is. This stuff caused problems ever since it appeared. There have been known bugs and vulnerabilities caused by combined characters. More than t

Actually there is. This stuff caused problems ever since it appeared. There have been known bugs and vulnerabilities caused by combined characters. More than that, I don't think I can provide any references now, but I remember some vulnerabilities caused by improper implementation of emoji alone in applications supposed to support them. So both always were somewhat of a problem, except combining characters are obviously more important and hence more justified. Now we have both combined. What unexpected behavior this will lead to? None of us can know.