Help with frer.

Kind of wondering if I had a chemical... Tell me your thoughts....Cause today’s test was a BFN.

Took this test 2 days ago - shrugged it off as an evap (pic is tweaked -like vvvvvvvvvfl maybe?)

But noticed today that it had dried into this 👇🏻(not tweaked)- definite line if you zoom in.

Thoughts?