Oh I agree they're not that bad, and i'm not asking that Webtoon NOT have ads on those comics, and I'm not asking that they ask these creators to butcher their comics or censor or whatever. I just don't think the discover artists should have to butcher their comics as much as they have... Seems like a double standard.
Now I will admit I've never been blessed with a webtoon promotion, and quite frankly I doubt I ever will, so I'm not speaking from personal experience, but nearly all my friends have been promoted at some point in some way by webtoon and they all say the same thing- after a promo you lose 100s of subs, for weeks-month following the promo (unless you get promo again). The only exception being those who are on the top 5 list of their genre- they are essentially always getting exposure so they don't drop subs.
What's likely happening is you're still gaining subs, you're just losing more subs than you gain and having an overall net loss. But you can't look at it that way, you have to think of the big picture, you overall are growing more than had you not had the promo at all.
Just remember there are a lot of creators who never get the exposure opportunity that you have gotten, and losing 100 when you have 100,000 subs is only a 0.1% loss. That is such a small percent to lose.