I can't tell how usual it is. I think I was never low functioning at all.
I was conscious enough about everything what happened around me. But according how my parents described me in my childhood I could speak but badly. I learned to phrase sentences correctly when I was about 5 years old.
Then I started to show that I'm not low or middle functional autistic at all.
Which is why it’s so scary when children get that stamped diagnosis. It can turn out to be wrong. Did you have to go through special treatments or education?