You can define your terms how you like. The reason I think people are using the term “fakeout death” is that the show is creating the problems that fakeout deaths create in that it undermines the stakes and sense of mortal peril. If characters are fighting, I know from general life knowledge that if one of them gets stabbed through the chest, it will be fatal. Thus, I sense the peril and understand that the current conflict is high stakes. However, if it’s established in the universe that characters can simply heal each other from wounds that should be fatal, I no longer know what the stakes are. We are no longer in a universe where real world judgment can tell us what mortal peril even looks like.