What is happening?

Jill • 👶🏻💙 9/6/2019. 👼🏻 9/2020.

I got a peak this morning that is clear as day but then follow up tests today way lighter. I do drink a moderate amount of water during the day- but is that big of an immediate reduction in the test line normal?? I thought PM should show the highest concentrations? Was the peak OPK a fluke??