Can't find the link to the breakdown of the bug(s) and Blizz were being cagey on it (for obvious reasons) but /r/overwatch peps were reporting

1) Pilot D.VA could be shot in mech
2) De-Meching D.VA could cause the game to restart in a new map
3) Abusing the bug could also lead to full game crashes

So not a run of the mill bug!