I have no idea how many dpo I am, maybe 9/10 - I’m not trying to get pregnant but I’m a little confused has this happened to anyone else?

I took a FRER this morning with first morning see and the faintest line has come up, it’s pink with colour.. hard to see in pictures but don’t need to squint in real life to see it. I’ve just done another this evening after a 4 hour wee hold and there’s no line at all...

Has this happened to anyone else?

Top is the one with a line, the bottom is the no line..

Appreciate any advice or help thank you