I don't know where the lightbox image comes from

I have a problem for days, which I can’t solve… I feel like it looks easy, but I just can’t solve it
I have a lightbox, which when I click on it, a gallery appears with another image that I don’t know where its link comes from, in every image that I click on, this bike image appears… but in the lightbox, I didn’t put a link to it
Anyway, if anyone can help me =)