Is Glow reliable on checking OPKs?

J • Samuel 11/9/17 and Amelia 09/19/19 and baby number 3 due July 2021

I’ve been checking my OPKs with Glow since I’m new at them. And today about 3 I took one and glow said it was positive. Just wondering how reliable Glow is. It said it’s the first notch on positive.