Is this dark enough for 4w1d? Not fmu took them at the same time

I used Tescos always have and tested 7 weeks ago got a faint line all 4 tests I done over a week so tried a different brand and it was negative. Maybe try a different brand and see what it says xx

Thanks ! I have 5 tests with faint lines I figured what are the chances they’re all invalid lol But I would expect the line to be darker , thus how it was with my first pregnancy