MC is crazy too tho? A red flag is someone who harms and does unforgivable things. Yeah it was probably too early to call him a green flag but so far he hasn't shown any red flags either.
The way every other adult acts around him so far except Jinwoo IS a red flag what do you mean. In fact the way he's introduced to the reader, the utter callousness with which he decided whether to save MC's life or not was a red flag. And the question of how this town maintains tranquility while the general society seems to have crumbled is the other red flag. The original meaning of a "red flag" is that it is a signal that warns others of danger, and it became a description for romantic leads whose behaviour fit a dangerous pattern *before* they did the unforgivable things to the MC.
It's hard to miss the strange note of insincerity in Guwon's "You hurt my feelings" performance, even as the impulse behind him removing the rings seems sincere and he seems to truly desire Jinwoo's trust. I suspect it has something to do with his strong Frankenstein's monster vibes.
I have no idea why people are/were calling Guwon a green flag. from the beginning it's clear as day that he seems to be fucking crazy