I dunno, man. Reading the email I got I don't see it as that bad? Unless you draw porn/erotica, which isn't allowed on most sites anyway with the graphic sex scenes and all. (Regardless, it sucks for people trying to make a living)
Look at the Adsense addition, it seems to be a different thing than Discover Policy. If you want to sign up for the ad program via Google your work has to be child friendly. Which Webtoons was originally advertised as a PG-13 site to begin with, and they just recently added the 17+ content warning pop-ups.
Although I'm not sure how this whole thing will affect the original eligibility program Discover has. Maybe they're changing that over to the Google thing? If so, that sucks.
Also kinda surprised that none of my pages got taken down yet since some have visual depictions of drug use, alcohol consumption, nudity, and a non-graphic depiction of suicide. I guess time will tell.