Totally with you OP. I was often told I was quiet or shy as a child, by teachers etc, in a way that made clear it was a negative trait and something to be worked on.
These days, I know I can be quite reserved and am quiet in big groups especially, but I'm sociable and friendly, I can make conversation easily and have a laugh with people.
I went to a destination wedding a few years ago and all the guests had great fun together at a few parties and events before the big day. A friend of the groom who I'd never met before, and incidentally was really loud and outgoing, randomly one night came over specifically to ask me 'why are you always so quiet?'.
It's honestly crushing. What are you supposed to say to that? I thought I was getting on well with everyone, having a nice time, laughing and getting into the spirit of things. No I'm not leading the singalong or entertaining everyone with my dance moves like him. But then not everyone can.
When he said that, it felt like an accusation. He might as well have just came out and said 'what exactly is wrong with you?'.
It then makes you feel self conscious about the efforts you're making to chat. Like I'd rather just sink into a wall than try to join in and have people still think 'haha look at her trying to be normal'. Because there's obviously something so glaringly weird about me that makes people feel compelled to comment.
I'm fine with being quiet, I really am. But as soon as someone tells me I am, it takes me right back to being a self conscious child being told I need to speak up more. That's actually the last time anyone said that to me and it was about 6 years ago now, but if sticks with you.
If anyone reading this thinks it's ok to point out to people that they're shy or quiet, it's not. It's really not. We've heard it all our lives and whatever you might tell yourself, it's not a neutral or a positive comment to the person hearing it for the 1000th time.