Never heard of that before I’m not quite sure why the relevant to the situation though the astronaut one would have been better
The comic was called “Loss” because it was about the comic character losing his unborn child. It became a meme because it didn’t fit the tone of the comic series (normally about gaming and non serious stuff).
So now when anyone mentions the word “loss” (as OP did in the title of this post), people meme about it in some way. Usually by posting a minimalist version of the comic.