My man, I am glad to see that you are coming around. Here are a couple more clarifications.
1. We did not receive any "critical damage" buffs. This was nexon's poor choice of wording to say that we will do more damage (we don't, this was a lie, 100% all the way)
2. This patch not only nerfed Kanna's support, it also nerfed endgame Kanna solo damage, we did not receive ANY buff at all this patch, despite what the devs think
3. Kannas do not deal 20-30% less damage than other classes. We deal roughly 50% less damage than the best classes, and 40% damage less than most other DPS classes. Endgame Kannas peak at around 250-260b/s, whereas endgame nightwalkers peak at 500b/s+. Other sub DPS classes that have support functions like Battlemage (~320b/s), Mechanic (~320b/s), Dawn Warrior (~450b/s) are all still significantly better than Kanna. Kanna is the single lowest damage class in the whole game by a significant margin
4. You are having a really rough time progressing your kanna because this class is complete garbage. You would have a much easier time attempting chaos vellum and normal lotus on pretty much any other class in the game
5. This is why there are so many Kanna feedback threads here. We are trying to get our class improved for once, after receiving continuous nerfs patch after patch for a year and a half. The thread hosts all know that the state of Kanna is trash, so its not helpful that you keep disagreeing when you clearly are new to the game and don't have a basis of comparison for what is strong and what is weak.
6. You should quit your Kanna and change mains if you want to progress. You will progress way faster this way.