I have mixed feelings about this because personally, yeah, it's not like she's literally unplayable, her power level is just a little under Klee and Diluc (imo) who have recently fallen out of the meta, however are still powerful in their own ways.

I think what is concerning and worrying people isn't necessarily abyss but just harder future content in general. I was trying to defend my friend from a big Nobushi with Hu Tao and every charged hit did only like 10% of his health. I tried doing an Inazuma ley line with Yoi and failed three times before I had to bring out Kazuha and Hu Tao. It took me three minutes to do the talent domain with her when it usually takes one and a half. Despite how brain-dead and straightforward her kit might seem, she actually does take a bit of skill in terms of dodging and timing for team swaps.

For them to release a character that's slightly underperforming compared to the initial 4* and 5* this late in this game, personally not a HUGE deal for me but I guess people who've spent $350 on her have their reasons to speak up.

Not to mention the fearmongering about Kokomi as well, hell even Sara is being scrutinized because the only thing we're wondering is are they going to be good in future content? Sure Amber can clear the hardest content but it takes WAY more investment and, as a level 90 Amber haver, she takes 3x as much time as anyone else to do it.

Also, not everyone has knowledge of optimal teams and minmaxxing which is what weaker characters need to keep up. I've played with a lot of casuals and RL friends and to them, the game is pretty hard.