Chemical?

I’m on day 3 of heavy period, but around 10 dpo started getting faint lines (different brands), today the lines continue and are a slight bit darker.

They’re still considered faints in my opinion though, it’s a chemical right? If any of you ladies have had one before do lines continue to show until after you’re done with period? I was thinking they’ll eventually go away but just took a test without any hold and still appears to be getting slightly darker.