I really don't think that's true at all. I consider drowning to be inhaling water and being unable to breathe, not just any death that happens underwater, and I imagine most people would think the same.
Sure. The people who said they have drowned probably think the same. But it doesn’t mean that they have carefully considered all the possible failure modes of a submersible and postulating that one which leads to a drowning is the most likely in this case. It expresses more a vibe that the speaker thinks they are dead.
But why not make it more concrete. Can you find a single example where someone says that they have drowned and the speaker means it as a carefull engineering analysis regarding failure modes, as opposed to a general vibe of “they dead”?
