I mean...it was more than "half" in terms of quantity. It was basically the meat and potatoes of the PvE gameplay, and we're left with basic PvE story missions with locked heroes that will largely play exactly the same as they do in PvP.
So it was "half" the PvE, but if we're being pedantic here in terms of, "Not all PvE was canceled" and such we should acknowledge that basically half of Overwatch 2 as a whole just got nuked from orbit. The half that was supposed to actually add something new beyond more maps and heroes and such. Story missions are nice and all but they're not gonna keep players coming back for more.