Faint lines

Patricia • Mother to 👦🏻(15)👦🏼(4)👶🏻(1) and 👼🏻👼🏻👼🏻👼🏻👼🏻. Pregnant 🤰 due Dec 28!

I’m confused on my pregnancy tests. Why would yesterday’s be very faint when two days ago and today’s is darker?