Are early blood tests accurate?

Has anyone done an early blood test to find out your baby’s gender? Was it accurate?

I haf harmony test at 9 weeks
Due to my age with #4. It was 100% accurate

I have a Facebook friend who did the blood test & it came back saying she was having a boy & they even did a gender reveal party then yesterday she had her appointment to find out gender of the baby & the baby is a girl so she did a post on Facebook yesterday saying Plot Twist w/girl ultrasound pictures