Has anyone had any experience having an NIPT test that was wrong?

I am 25 years old, have had 3 healthy pregnancies that gave me beautiful healthy boys and today my doctor had me come in to tell me that my baby has a 75% chance of having Trisomy 21. They are going to schedule more testing/ultrasounds.

But I’m just curious if I need to be worried/start planning accordingly?

Has anyone experienced this?