Is this fungus?

https://preview.redd.it/9id7c1fk8prh1.jpg?width=3024&format=pjpg&auto=webp&s=d1c941ce012c2efb043f45a2026839ce48e54963

Hi, I just received this Mamiya 6 in the mail. While inspecting it, I noticed something that looks a bit like a worm in the viewfinder. Is this fungus or something, or is this completely normal? It looks way worse under direct light. Under normal light, it’s not that noticeable. I would really appreciate some help from someone with more experience regarding this.