Clearblue and FRER??

Rebecca

I took a clearblue 2 days ago and thought I may have seen something but then it looked like a dye run. So I took the other one in the packet this morning thinking it would look the same but I feel like I can see a clear faint line? I then took a FRER and it looks negative 🤔 I've heard that these tests aren't great, is this why?