Truly, deep down Amber was never mean.
Some could say i'm bias because I love Dove Cameron but i'd like to express my opinion anyway.
Amber is portrayed as a very snobby, selfish, egotistical and narcissistic character until the very end of the movie where she is shown joining in to dance with Tracy and the others.
Personally i think all of this was shoved onto her by her mother as it was always Velma telling Amber what to do like when when she was already in frame of the camera like all the others Velma said to her "Amber... Hog the camera." and so she did and listened to her mum. I also felt the relationship with Link was very forced on her by Velma specifically for The Corny Collins Show, I mean, yes, Amber did ask Link to meet her under the bleachers at some point in the movie but I believe Amber was just doing what she thought her mother wanted, hanging around with boys. My other point of Amber just being controlled by her mother is the scene in the record store when Velma says "Amber come" as if she's calling a dog and of course Amber listens and follows her mother out of the shop.
You could say "Oh, but she was so mean to Tracy and Penny!!" but again, i think this was brought on by Velma who already had a hatred for anyone who didn't look like her, she found herself superior and brought this ideology onto her daughter. During "Mama I'm a Big Girl Now" Velma tries shoving shoulder pads into Amber's bra to make her look more "appealing" which leads me onto another theory of mine that Amber constantly struggled with being worried that she wasn't going to be good enough for her mother so she always tried so hard to do her best, basically becoming her mother in order to impress her which meant going with Velma's ideology.
So anyways that's just my opinion on Amber, i believe if she didn't have Velma controlling her, pressurising her and basically trying to make her an exact copy of her she would be a nice and sweet girl.
I do have headcanons for her that kind of stem off of this and also because she's my favourite character and she needs to be awarded with being a wlw. But my headcanon is she's lesbian but it's been engraved into her brain by her mother that being queer is a disease (it was the 60s what would you expect?) that she denied any attraction to a woman. This would also result in her being comphet because of the obvious pressurisation from her mother and most of society in those days. I also say this because I honestly can't see her happily with a man, I feel she'd want someone gentle and soft , who understands her and cares for her, a girl specifically.
