I agree with Howdy that it seems more like an issue with the school/class management. Your description seems to show that the school has embedded a huge importance on age relative to grade that the other children are reflecting back.
ITA with howdy and notnafnaf re that this seems to be an issue with the school. It also sounds (to me) like it's a school that's very focused on achievement perhaps more than exploration and learning for the sake of learning - and honestly, this is only kindergarten. I'm just wondering if, overall, you might ought to think about what other *school* options are available, rather than wondering if your dd should have or shouldn't have been accelerated.
She sounds miserable at school - is this a small school with only one kindergarten class, or are there other classes? If so, could you ask to move her to a different classroom? Then look at options for different schools? If you don't have other options for moving her to a different school or at least a different classroom, I'd consider taking her out of school this year. Acceleration might happen anyway next year, or if she's not ready next year, it doesn't mean she won't be ready and able to accelerate in a future year. JMO, but I believe a child's mental health and developing their self-image is much more important than the grade they are in during the school day. If you pay attention to that, the rest should sort itself out.
Best wishes,
polarbear
