Once I lost about 100 subs overnight a few years ago... :'D
My guess is it was because of a profile wall post I'd made. I talked about my pathological anxiety and how it affected me as a comic creator. And I guess that was too personal/negative for some people?
In retrospect, I probably could've spared some of the details. Overall though, I don't regret making that post, because the comic itself is a reflection on my anxiety (or rather, what caused the anxiety). It was an honest message that was thematically relevant to the comic, although in a roundabout way.
I know some people don't want to see ANY creator negativity because they see it as attention whoring. Which it was not intended to be. Then there are also people who just don't need any more negativity in their life. Whatever their reason, it's their prerogative to unsub, sooooo...