Wrong about gender

So I have my anatomy scan on Monday, and I’ve been seeing a lot of posts on here about the ultrasound tech being wrong about the gender, and I’ve seen a lot of woman questioning whether or not the ultrasound tech got it right. Is this a common thing??? Are they wrong often??? It worries me to think about being told a gender and preparing a nursery and then it ends up being the opposite gender. I’m a FTM so I’ve never experienced any of it before.